explain xkcd:User: Aprilfoolsupdate!

Wow what? I can create my user page now! Yay!
About me: basic knowledge of html, nothing else
My signature: ^April_fools^update!(talk)
I like my signature, don’t touch it.
Leaderboard for top 50:

Aprilfoolsupdate!
Aprilfoolsupdate!
Born date	Not telling
Planet	Earth [citation needed]
Language	English
Stellar system	The solar system

Last 7 days (Top 50)

Rank Score Pages Changes Username 1 5,747 5,725 5,849 DollarStoreBa'al 2 1,631 1,616 1,675 Victoria 3 22 18 22 TheusafBOT 4 13 4 25 Trimutius 5 11 7 11 Utdtutyabthsc 6 10 7 10 R128 7 7 4 7 Lp0 on fire 8 7 2 8 boB 9 6 3 6 Kivi Shapiro 10 5 3 4 Headphones the stickman 11 5 3 4 BunsenH 12 5 2 4 Kynde 13 4 2 3 Fephisto 14 4 1 3 SammyChips 15 4 1 3 Magtei 16 3 1 2 Questioner 17 3 1 2 Beechmere 18 3 1 2 Stephan Leeds 19 3 1 2 Logalex8369 20 3 3 3 Batbrain55 21 2 2 2 KelOfTheStars! 22 2 2 2 ISaveXKCDpapers 23 2 2 2 August Fuller 24 2 2 2 Starnote 25 2 2 2 AgentMuffin 26 2 2 2 Qoiuoiuoiu 27 2 2 2 first last 28 2 2 2 Theusaf 29 1 1 1 Ictlogist 30 1 1 1 Rory O’Kane 31 1 1 1 Daniel Griscom 32 1 1 1 Cobl703 33 1 1 1 Kirinhatchi 34 1 1 1 Sean McDonough 35 1 1 1 Planer28 36 1 1 1 Lallero 37 1 1 1 I’m gonna fix this 38 1 1 1 David Garfield 39 1 1 1 EpicRedhead13 40 1 1 1 Mathmaster 41 1 1 1 GreatWyrmGold 42 1 1 1 1234231587678 43 1 1 1 Michael Valler 44 1 1 1 CalibansCreations 45 1 1 1 Heleatunda 46 1 1 1 DKMell 47 1 1 1 XkUjlmoh 48 1 1 1 Darth Vader