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 day (Top 50)

Rank Score Pages Changes Username 1 8 2 12 RadiantRainwing 2 5 2 4 Paintspot Infez 3 5 2 4 DollarStoreBa'al 4 4 2 3 Fephisto 5 3 1 2 管委会篝火无法解放军“赐额“你去呢管理哦法？ 6 3 1 2 New editor 7 3 1 2 Duralumin-here 8 3 1 2 GSLikesCats307 9 3 1 2 Machina Lucis 10 2 2 2 Trimutius 11 1 1 1 Sturmovik 12 1 1 1 Alcatraz ii 13 1 1 1 Angel Wedge 14 1 1 1 Salsmachev 15 1 1 1 Elektrizikekswerk 16 1 1 1 Barry Margolin 17 1 1 1 1234231587678 18 1 1 1 John Hawkinson 19 1 1 1 Steve Spivey 20 1 1 1 Victoria 21 1 1 1 Jacob Thrall