We saw the EU team's World of Warcraft efforts earlier with the P1mp My Mount feature, now their US counterparts have revealed their annual joke.
Last year came the Bard, a new class that had a user interface similar to Guitar Hero, where players could attack others using "awesome chords" and such. This year, we have the Dance Battle system headed up by bad guy Kael'thas Sunstrider. Your "crew" will be able to have a dance-off against other crews, overseen by NPC dancemasters. A custom interface similar to the vehicle control provides players with a means to make the slickest moves to impress the judges.