Deadmau5 pranked Skrillex by wearing a t-shirt with Skrillex's personal cellphone number on it.
That's right, if you need to get ahold of Skrillex, just call 626-319-1039.
Update: Skrillex is now forwarding his calls to Deadmau5' phone. Deadmau5 is forwarding these calls to Markus Persson, creator of Minecraft. My son loves Minecraft.
Full disclosure: I'm not nearly cool enough to know what a Deadmau5 or Skrillex is, but thought this was a clever prank. Deadmau5, I understand, is Canadian, and that does earns him bonus points.