A metaphor used to describe taking an unusually messy or odorous shit in the toilet. Whitey refers to the toilet bowl, while killing it refers to the unpleasant act being committed against it.
The traditional, lyrically aggressive hip-hop sub-genre--dedicated to themes of violence, anarchy and social disruption; UNLIKE the current watered-down, lame-ass, mainstream dollar-driven verbal diarrhea...
Yo, you can't be playin' that kill-whitey music up in here; if bubba hears it, he gonna come kick some fuckin ass...
Commonly used in the Caribbean islands referring to their desire to kill white people. Considering the extensive use of slaves in the Caribbean, understandable.