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We have collaboratively explained Expression error: Unrecognised punctuation character ",". xkcd comics, and only Expression error: Unrecognised punctuation character ",". (Expression error: Unrecognised punctuation character ",".%) remain. Add yours while there's a chance!

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The nice thing about headcannnons is that it's really easy to get other people to believe in them.
Title text: The nice thing about headcannnons is that it's really easy to get other people to believe in them.


This comic is a pun on the homophones "canon" and "cannon".

A "canon" describes things that are true for a particular fictional world. The term is derived from the Biblical canon, a list of books considered to be authoritative scripture by a particular religious community. A work's definitive canon is determined by its creators, but fans can have their own personal canons — things that they believe should be true for the setting, such as new romantic pairings or personal answers to questions officially left unexplained. Such a term for a canon that only exists in that fan's head is, thus a "headcanon". Depending on the person, new headcanons can be frequently invented in response to ideas or realizations that pop up out of nowhere (hence the comic's first panel); some are simply strange or unconvincing, but others can be notoriously contagious and even sometimes return to the author, who may decide to officially canonize them.

A cannon, meanwhile, is an explosive-based projectile weapon. While the more esoteric headcanons are easy to ignore, it is decidedly more difficult to not notice or believe the existence of a cannon strapped to one's head.

Randall addresses both homophones in the title text by putting three consecutive "n"s in "headcannnon".

This may also be a nod to the common internet phrase "head cannon" (meaning something was so surprising, unthinkable, or annoying) as a literal and destructive cannon on Black Hat's head.


[Black Hat walks in.]
Black Hat: New headcannon:
[Cueball is sitting at his desk, using his computer.]
Cueball: Yeah?
[Black Hat lifts his hat, revealing his "headcannon": a tiny cannon on the top of his head. The headcannon fires and blows up Cueball's desk, the explosion throwing Cueball backwards.]
Headcannon: BOOM
Cueball: AUGH!

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