explain xkcd - User contributions [en]

221: Random Number

2013-09-23T21:35:23Z

148.87.19.222: /* Explanation */

{{comic
| number = 221
| date = February 9, 2007
| title = Random Number
| image = random_number.png
| titletext = <nowiki>RFC 1149.5</nowiki> specifies 4 as the standard IEEE-vetted random number.
}}
==Explanation==
The comic specifies a function (in a {{w|C (programming language)|C-like}} syntax), which should return a random number. Most functions of this form are random number ''generators'', implying that they return on subsequent calls ''different'' numbers. But the programmer has instead created a function that just returns always the same ''random'' number; random, because it was chosen by rolling a die as the comment documented. This function is essentially worthless, as it could simply be replaced by a "4" wherever it is used. And in fact, most modern compilers would do this automatically.

The comic also has a philosophical bent, by showcasing the limits of knowledge for an external observer. Someone who is calling this function, but unable to see its source code, will never be able to tell with 100% confidence whether the function is flawed. Even if she runs the function 10 times, and it always returns 4, there is always the possibility that it could be a fluke. As she runs the function more and more times, she can develop more confidence in the theory that the function is faulty. But unless she breaks the barrier and examines the source code itself, she will never be able to declare the function to be faulty with 100% confidence.

Despite the extreme example given, this is actually a practical problem which likely exists in the real world. If the function was more sophisticated but still had a 5% bias towards one number under certain circumstances, this would be extremely hard to notice & prove. More likely, the API users would continue to believe that the RNG is working as intended, without realizing the flaw inherent in it; anyone who grumbles about seeing 4 very frequently may even be accused of not understanding the non-uniform nature of randomness. Given the extremely large number of APIs & libraries present, and that not all of them are fully examined & understood by 3rd party experts, such flaws are likely present in our world as well. These flaws may even have been purposely introduced by a malicious agent or entity seeking to exploit them.

The {{w|IEEE}} is the organization responsible for maintaining a number of computer standards. An RFC, or {{w|Request for Comments}}, is a formal document put out to computing experts by {{w|IETF}} in the hopes of becoming a future standard. However, RFC 1149 was an {{w|April Fools' Day Request for Comments|April Fools' joke}}, defining how carrier pigeons have to be used to transmit Internet packets. Ironically, although the RFC was written in 1990, a homing pigeon with a couple microSD cards tied to its leg might well be faster than your typical consumer Internet connection in the US today. The <nowiki>RFC 1149.5</nowiki> simply does not exist.

==Transcript==
int getRandomNumber()
{
return 4; //chosen by fair dice roll.
//guaranteed to be random.
}

{{comic discussion}}
[[Category:Programming]]
[[Category:Computers]]

1261: Shake That

2013-09-23T20:15:46Z

148.87.19.222: /* Edited out unnecessary details. I think people can understand that 2+2=4, without a lecture about calculus. */

{{comic
| number = 1261
| date = September 6, 2013
| title = Shake That
| image = shake that.png
| titletext = How do I work it? IT'S ALREADY WORKING!
}}

==Explanation==
Visiting a club, [[Megan]] is exhorted by a phrase used in several songs, to "shake what your mama gave you", a crude euphemism typically used to encourage shaking one's body parts (referring to any of the sexually appealing anatomical parts of the dancer). Taking this exhortation extremely literally, Megan proceeds to locate a mug presumably given to her by her "mama" labeled "World's greatest daughter" and shakes it.

The line "shake what your mama gave ya" has been used since 1992 when it was the title of a song by {{w|Poison Clan}}, a southern hip-hop group that was influential from 1990-1995. Another version by Stik-E & Da Hoodz was released a year later on Phat Wax records. The line gained a wider audience when it was sampled by {{w|Fatboy Slim}} in the similarly titled "Ya Mama" on his 2000 album ''{{w|Halfway Between the Gutter and the Stars}}''. More recently the line was featured in the {{w|Lil Jon}} single "Stick That Thang Out". In fitting with the general thematic composition of such a song, a large part of which revolves around either goading a woman to, or describing one who is dancing seductively in a nightclub - this line asks a girl to sway her hips, buttocks, or breasts.

The title text refers to another lyrical cliche, "work it", which typically refers to "working" one's body; again, generally seductively. The action may be considered work either from the point of mechanical work, or as a reference to a professional dancer. This naturally leads Megan to further confusion (as indicated by the title text) when taken literally, as she responds "it's already working!" It is not entirely clear if she is again referring to the mug, or simply another generic object not displayed in the comic.

==Transcript==
:[Megan stands in a disco, surrounded by dancing figures. She looks confused.]
:PA system: Shake what your mama gave you
:Megan: ???
:[Megan walks out of the club door.]
:[We see a mug on a table, labelled "World's Greatest Daughter".]
:[Megan shakes the mug.]

{{comic discussion}}
[[Category:Comics featuring Hairy]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics with color]]
[[Category:Language]]
[[Category:Music]]

Talk:1261: Shake That

2013-09-23T20:12:01Z

148.87.19.222:

Worst xkcd Ever! [[Special:Contributions/78.55.145.25|78.55.145.25]] 08:31, 6 September 2013 (UTC)

Hey, it's not the worst xkcd ever. What about the early xkcd strips, where most of them were just sketches or drawings? [[User:GameZone|GameZone]] ([[User talk:GameZone|talk]]) 08:37, 6 September 2013 (UTC)

Surely "Worst. xkcd. Ever!" No? Turning to the explanation, I like the phase lag explanation. Never thought of sexual exhibitionism in those terms before.--[[Special:Contributions/203.166.249.26|203.166.249.26]] 08:46, 6 September 2013 (UTC)

:The explanation is definitely pushing this strip up. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 09:30, 6 September 2013 (UTC)

Hugely impressed by the explanation. I would never have thought you could write so much about such a dry comic. --[[User:Mynotoar|Mynotoar]] ([[User talk:Mynotoar|talk]]) 09:34, 6 September 2013 (UTC)

This explanation makes me so happy. Make an account, anonymous user at IP 220.224.246.97 and come collect your praise for such a great explanation! --[[User:Jeff|<b><font color="orange">Jeff</font></b>]] ([[User talk:Jeff|talk]]) 15:27, 6 September 2013 (UTC)

Perhaps the XKCD website was hacked? {{unsigned ip|‎88.174.225.205}}

Truly stunning explanation. Come and collect your internets. [[Special:Contributions/78.105.231.184|78.105.231.184]] 20:49, 6 September 2013 (UTC)

Haha, PHASE LAG cracked me up. Props for the explanation; I didn't understand the comic at all. {{unsigned ip|223.239.158.130}}

:+++1 for the whole *phase lag* line!{{unsigned ip|92.230.220.144}}

To the nay-sayers: "<nowiki>[XKCD is]</nowiki> A webcomic of romance, sarcasm, math, and '''language'''." Quit with the downers, man, and get with the groove!

(Also, it'd probably be a general rule that, paid-for bodysculpting aside, a girls breasts and/or buttocks have a good chance of being like those of her mother. Thus she 'gives you'(/her) that big butt (''not'' a universally desirable feature amongst womankind) or set of boobies that the DJ/MC/whoever is probably after encouraging the physical highlighting of. But that's a boring (and only half right) detail about the explanation. All praise to the current version, and don't add any more to it on my account.) [[Special:Contributions/31.126.86.231|31.126.86.231]] 19:17, 7 September 2013 (UTC)

Interpreting a "yo mama" line literally was also done in [[502: Dark Flow]]; that connection may give this one similar poignance... [[Special:Contributions/90.197.95.152|90.197.95.152]] 19:24, 7 September 2013 (UTC)

Female breast endowment genes don't express in men. Therefore, although a woman's breast size will about equally correlate (on average) with her maternal grandmother as with her paternal grandmother, it is most definitely more correlated with her mother's bust size than her father's. I'm trying to find a way to add that to the explanation too, but can't find the right pithy phrasing. [[User:Djbrasier|Djbrasier]] ([[User talk:Djbrasier|talk]]) 20:20, 7 September 2013 (UTC)

This is now my favorite description --[[Special:Contributions/108.3.190.56|108.3.190.56]] 21:04, 8 September 2013 (UTC)

Moved out of main explanation, and here, since it is tangential:
While the line is used in a male-watching-female context, there is nothing to preclude the reverse, or indeed any alternative sexual orientation and fetishes. It is, however, an applicable one if he/she considers his/her body as something given to her by her mother. This is not entirely spurious a consideration either. Aside from the fact that each human child starts off as an egg in the mother's body, with only a small percentage (at an atomic mass accounting level) of mass inherited from the father, almost all the anabolic material responsible for conferring the birth mass of a baby is obtained through the mother - and from the nutrients she processes. Additionally, female breast size genes don't generally affect bust size in men. Therefore, although a woman's breast size will about equally correlate (on average) with her maternal grandmother as with her paternal grandmother, it is most definitely more correlated with her mother's bust size than her father's.

1261: Shake That

2013-09-23T20:11:00Z

148.87.19.222: /* Moved out of main explanation, since it is an extreme tangent */

{{comic
| number = 1261
| date = September 6, 2013
| title = Shake That
| image = shake that.png
| titletext = How do I work it? IT'S ALREADY WORKING!
}}

==Explanation==
Visiting a club, [[Megan]] is exhorted by a phrase used in several songs, to "shake what your mama gave you", a crude euphemism typically used to encourage shaking one's body parts (referring to any of the sexually appealing anatomical parts of the dancer). Taking this exhortation extremely literally, Megan proceeds to locate a mug presumably given to her by her "mama" labeled "World's greatest daughter" and shakes it.

The line "shake what your mama gave ya" has been used since 1992 when it was the title of a song by {{w|Poison Clan}}, a southern hip-hop group that was influential from 1990-1995. Another version by Stik-E & Da Hoodz was released a year later on Phat Wax records. The line gained a wider audience when it was sampled by {{w|Fatboy Slim}} in the similarly titled "Ya Mama" on his 2000 album ''{{w|Halfway Between the Gutter and the Stars}}''. More recently the line was featured in the {{w|Lil Jon}} single "Stick That Thang Out". In fitting with the general thematic composition of such a song, a large part of which revolves around either goading a woman to, or describing one who is dancing seductively in a nightclub - this line asks a girl to dance, thereby swaying her hips & buttocks, or breasts, the most common male 'fetishes' - making them more conspicuous because of the phase lag with the rest of the body, which may be attributed to non-rigidity of the elastic structures in the usually dim ambiance, for purposes of her male audience's gratification (whether it be solicited or voyeuristic).

The title text refers to another lyrical cliche, "work it", which typically refers to "working" one's body; again, generally seductively. The action may be considered work either from the point of mechanical work, or as a reference to a professional dancer. This naturally leads Megan to further confusion (as indicated by the title text) when taken literally, as she responds "it's already working!" It is not entirely clear if she is again referring to the mug, or simply another generic object not displayed in the comic.

==Transcript==
:[Megan stands in a disco, surrounded by dancing figures. She looks confused.]
:PA system: Shake what your mama gave you
:Megan: ???
:[Megan walks out of the club door.]
:[We see a mug on a table, labelled "World's Greatest Daughter".]
:[Megan shakes the mug.]

{{comic discussion}}
[[Category:Comics featuring Hairy]]
[[Category:Comics featuring Ponytail]]
[[Category:Comics featuring Cueball]]
[[Category:Comics featuring Megan]]
[[Category:Comics with color]]
[[Category:Language]]
[[Category:Music]]

1265: Juicer

2013-09-23T19:58:36Z

148.87.19.222: /* Explanation */

{{comic
| number = 1265
| date = September 16, 2013
| title = Juicer
| image = juicer.png
| titletext = But the rind is where all the vitamins are!
}}

==Explanation==
{{incomplete}}
;Juicing Gushers
Juicers are typically used to crush fruits and/or vegetables, thereby extracting the liquid juice and eliminating the task of chewing the solids. However, in this case, instead of actual fruits or vegetables, someone is making juice from {{w|Fruit_Gushers|fruit gushers}}, a chewy fruit-flavored candy, thereby extracting a nearly nutritionless artificial "juice" out of a candy casing which was formulated specifically for human consumption.

This may or may not be a parody of recent "fruit gushers" television commercials, in which fruit gushers are shown to squirt out nearly limitless amounts of "juice".

The title text asserts that the rind is where all the {{w|Vitamin|vitamins}} in the fruit reside. This is a common belief of actual fruits, although it is an untrue {{w|Urban legend|urban legend}} for many fruits; even fruits like apples do not contain most of the {{w|fiber}} and many {{w|Antioxidant|antioxidants}} in the skin itself, but rather directly below; although when you peel an apple you remove more than just the skin, losing also that area with high fiber and antioxidant content anyway. There is a simple rule: If your thumbnail can reach the flesh of a fruit don't remove the skin. It is absolutely absurd as in this case, though, as the "rind" of a Fruit Gusher consists mainly of sugar. This text mocks the usual sentiment that the less desirable part of a food is the part that is "better" for you.

The comic is thus also a parody of the notion that buying a juicer (or other things like exercise equipment) will automatically make people healthier. Here it is shown that what you do with the juicer is the relevant factor (for example, if one juiced solely apples every day, they would not get nearly the same nutritional benefits as someone who juiced other fruits and vegetables with more and varied nutrients).

The comic can also be interpreted as parodying the idea of fruit juices being healthy. Though this is widely believed, [http://well.blogs.nytimes.com/2013/07/31/making-the-case-for-eating-fruit/ recent studies ][http://well.blogs.nytimes.com/2013/09/04/some-fruits-are-better-than-others/ demonstrate otherwise.]

An alternative reading that expands on that theme is that the comic shows a juicer with three full bottles of real juice, indicating that the owner of the juice machine is making regular juice with the intention of drinking it, but not consuming juice at the rate it is produced. The comic also shows a Fruit Gusher snack, indicating the unhealthy option that the juicer owner just can't stop eating. But the color of the juices makes the first explanation more likely.

;Linguistic note on Hard '''g''' vs soft '''g''' and ways of pronouncing '''c'''
Some native English speakers may think that some non-native English speakers may think that "Gushers" /ˈgʌʃərz/ should be pronounced as "juicers" /ˈdʒusərz/. I.e., if you know enough to be dangerous about English spelling you could think that both words are pronounced /ˈdʒuʃərz/, but that's non-sense. Never the less...
*The plain-English word "gush" (meaning to flow rapidly) is pronounced with a hard 'g' and a 'u' as in 'flush' or 'gut.'
*The American television commercials for this product make it absolutely clear that "Gushers" is also pronounced with a hard 'g' and the 'u' as above.
*A 'g' can signify a soft-g sound (/dʒ/ as in 'gin'). However, natives know that the soft-g sound never appears in the combination "gu".
*A 'u' can signify a {{w|Close_back_rounded_vowel|close back rounded vowel}}, /u/ as in 'flute,' but that is exceedingly rare when the 'u' follows a hard 'g' (gun, gull, gut, gum, Gus).
*The letter 'c' can be pronounced /ʃ/ as in 'ocean' /ˈoʊʃən/. The pronunciation of 'cer' as /ʃər/ is not common, except in dialectical words like "[http://dialect.redlog.net/staticmaps/q_36.html grocery"].

==Transcript==
:[We see a shelf. On it, from left to right, are: a bag of fruit gushers; a juicer; a bottle of bright red liquid; a bottle of bright blue liquid; and another bottle of bright red liquid.]
:"Oh yeah, juicers are great! I use mine all the time."

{{comic discussion}}

[[Category:Comics with color]]

1265: Juicer

2013-09-23T19:57:29Z

148.87.19.222: /* Explanation */

{{comic
| number = 1265
| date = September 16, 2013
| title = Juicer
| image = juicer.png
| titletext = But the rind is where all the vitamins are!
}}

==Explanation==
{{incomplete}}
;Juicing Gushers
Juicers are typically used to crush fruits and/or vegetables, thereby extracting the liquid juice and eliminating the task of chewing the solids. However, in this case, instead of actual fruits or vegetables, someone is making juice from {{w|Fruit_Gushers|fruit gushers}}, a chewy fruit-flavored candy, thereby extracting a nearly nutritionless artificial "juice" out of a candy casing which was formulated specifically for human consumption.

This may or may not be a parody of recent "fruit gushers" television commercials, in which fruit gushers are shown to squirt out nearly limitless amounts of "juice".

The title text asserts that the rind is where all the {{w|Vitamin|vitamins}} in the fruit reside. This is a common belief of actual fruits, although it is an untrue {{w|Urban legend|urban legend}} for many fruits; even fruits like apples do not contain most of the {{w|fiber}} and many {{w|Antioxidant|antioxidants}} in the skin itself, but rather directly below; although when you peel an apple you remove more than just the skin, losing also that area with high fiber and antioxidant content anyway. There is a simple rule: If your thumbnail can reach the flesh of a fruit don't remove the skin. It is absolutely absurd as in this case, though, as the "rind" of a Fruit Gusher consists mainly of sugar. This text mocks the usual sentiment that the less desirable part of a food is the part that is "better" for you.

The comic is thus also a parody of the notion that buying a juicer (or other things like exercise equipment) will automatically make people healthier. Here it is shown that what you do with the juicer is the relevant factor (for example, if one juiced solely apples every day, they would not get nearly the same nutritional benefits as someone who juiced other fruits and vegetables with more and varied nutrients).

The comic can also be interpreted as parodying the idea of fruit juices being healthy. Though this is widely believed [http://well.blogs.nytimes.com/2013/07/31/making-the-case-for-eating-fruit/ recent studies ][http://well.blogs.nytimes.com/2013/09/04/some-fruits-are-better-than-others/ demonstrate otherwise.]

An alternative reading that expands on that theme is that the comic shows a juicer with three full bottles of real juice, indicating that the owner of the juice machine is making regular juice with the intention of drinking it, but not consuming juice at the rate it is produced. The comic also shows a Fruit Gusher snack, indicating the unhealthy option that the juicer owner just can't stop eating. But the color of the juices makes the first explanation more likely.

;Linguistic note on Hard '''g''' vs soft '''g''' and ways of pronouncing '''c'''
Some native English speakers may think that some non-native English speakers may think that "Gushers" /ˈgʌʃərz/ should be pronounced as "juicers" /ˈdʒusərz/. I.e., if you know enough to be dangerous about English spelling you could think that both words are pronounced /ˈdʒuʃərz/, but that's non-sense. Never the less...
*The plain-English word "gush" (meaning to flow rapidly) is pronounced with a hard 'g' and a 'u' as in 'flush' or 'gut.'
*The American television commercials for this product make it absolutely clear that "Gushers" is also pronounced with a hard 'g' and the 'u' as above.
*A 'g' can signify a soft-g sound (/dʒ/ as in 'gin'). However, natives know that the soft-g sound never appears in the combination "gu".
*A 'u' can signify a {{w|Close_back_rounded_vowel|close back rounded vowel}}, /u/ as in 'flute,' but that is exceedingly rare when the 'u' follows a hard 'g' (gun, gull, gut, gum, Gus).
*The letter 'c' can be pronounced /ʃ/ as in 'ocean' /ˈoʊʃən/. The pronunciation of 'cer' as /ʃər/ is not common, except in dialectical words like "[http://dialect.redlog.net/staticmaps/q_36.html grocery"].

==Transcript==
:[We see a shelf. On it, from left to right, are: a bag of fruit gushers; a juicer; a bottle of bright red liquid; a bottle of bright blue liquid; and another bottle of bright red liquid.]
:"Oh yeah, juicers are great! I use mine all the time."

{{comic discussion}}

[[Category:Comics with color]]

221: Random Number

2013-09-23T19:30:40Z

148.87.19.222: /* Deeper Explanation by whacks*/

{{comic
| number = 221
| date = February 9, 2007
| title = Random Number
| image = random_number.png
| titletext = <nowiki>RFC 1149.5</nowiki> specifies 4 as the standard IEEE-vetted random number.
}}
==Explanation==
The comic specifies a function (in a {{w|C (programming language)|C-like}} syntax), which should return a random number. Most functions of this form are random number ''generators'', implying that they return on subsequent calls ''different'' numbers. But the programmer has instead created a function that just returns always the same ''random'' number; random, because it was chosen by rolling a die as the comment documented. This function is essentially worthless, as it could simply be replaced by a "4" wherever it is used. And in fact, most modern compilers would do this automatically.

The comic also has a philosophical bent, by showcasing the limits of knowledge for an external observer. Someone who is calling this function, but unable to see its source code, will never be able to tell with 100% confidence whether the function is flawed. Even if she runs the function 10 times, and it always returns 4, there is always the possibility that it could be a fluke. As she runs the function more and more times, she can develop more confidence in the theory that the function is faulty. But unless she breaks the barrier and examines the source code itself, she will never be able to declare the function to be faulty with 100% confidence.

Despite the extreme example given, this is actually a practical problem which likely exists in the real world. If the function was more sophisticated but still had a 5% bias towards one number, under certain circumstances, this would be extremely hard to notice & prove. More likely, the API users would continue to believe that the RNG is working as intended, without realizing the flaw inherent in it; anyone who grumbles about seeing 4 very frequently may even be accused of not understanding the non-uniform nature of randomness. Given the extremely large number of APIs & libraries present, and that not all of them are fully examined & understood by 3rd party experts, such flaws are likely present in our world as well. These flaws may even have been purposely introduced by a malicious agent or entity seeking to exploit them.

The {{w|IEEE}} is the organization responsible for maintaining a number of computer standards. An RFC, or {{w|Request for Comments}}, is a formal document put out to computing experts by {{w|IETF}} in the hopes of becoming a future standard. However, RFC 1149 was an {{w|April Fools' Day Request for Comments|April Fools' joke}}, defining how carrier pigeons have to be used to transmit Internet packets. Ironically, although the RFC was written in 1990, a homing pigeon with a couple microSD cards tied to its leg might well be faster than your typical consumer Internet connection in the US today. The <nowiki>RFC 1149.5</nowiki> simply does not exist.

==Transcript==
int getRandomNumber()
{
return 4; //chosen by fair dice roll.
//guaranteed to be random.
}

{{comic discussion}}
[[Category:Programming]]
[[Category:Computers]]