New dances for everyone is the harlem shake.
Dinnerbone-because I binged your mother.
For some reason, I think the PvP changes, altthough I certainly hope not.
Hearthstone got way too much media attention to now even be considered an April Fools' joke. The timing is a bit weird, but I think that's real.
And I got my barbeque ready for Crabby, I swear!
The problem with April Fools is that a lot of the original joke ideas ended up becoming things people actually wanted, so when they turned out to be jokes, the community got uber butt mad.
Now, the April Fools jokes are obvious, but incredibly humorous and poke fun at the game and the community. I remember one year where if Mages counterspelled a Paladin it automatically respecced him to Holy, and if he already was Holy, it turned him into a Priest.
It's not tri-spec. Blizzard likes to "over-do" it. The never do anything believable, that's what makes them really funny. The bard class in itself is believable, but Blizzard just goes and overdoes it with the whole "guitar hero" gameplay. Tri-spec is something that is believable, and I can't really think of a way they can overdo it to make it funny.
The world that Punpun imagined stretched endlessly.
Wrynn becomes the new Horde leader.
Ysera goes crazy and fixes the world.
Org is completely gone and the horde cant access it. Player/ guild housing. OF COURSE CRABBY. Mages getting a nerf and Ret Paladins getting buffed. The list is endless I'm sure they'll find something that will give a good laugh.
Next raid in 2D-Jump and run style: Gamon kidnapped Aggra and we need to rescue her!