With origins from Halo 2 matchmaking, "Where dey at" was initially a slurred headset calling to teamates of "where are the players of the opposite team at". The term eventually evolved into a taunt statement upon headshot, betrayal, assasination, and sticky merkings.
Opposing Player X: (stands foolishly in coridoor underneath Lockout busy aiming w/sniper)

Me:(jumps down from behind and assasinates w/shotty.Where Dey At?(in direction of dead body waiting to respawn)
by gunsNalcohol September 27, 2007
Get the where dey at? mug.
the only question to be asked when searching for a BNH (butt naked hoe)
bird dick: ay bro where dey at?

bird dick 2.0: i dont know mane im tryna find em

bird dick 3.0: thaswassup
by bdmane October 20, 2009
Get the where dey at? mug.