PUG: (noun) A group of people who probably aren't finishing an instance today.
DEATH KNIGHT: (noun) What we'll call Ret Pallys after WotLK is released.
THE BARRENS: (noun) A section of the world where those who can't play, chat.
OVERPOWERED: (adjective) Anyone who beats me in PvP.
Those are all right, but I bet you all could come up with even better ones. Choose a term from WoW and "redefine" it to better describe what our world is really like.