Shit's goin down 

An expression used commonly to refer to a seemingly impending fight or confrontation that will usually result in someone or multiple persons getting the shit beat out of them. Often heard when one person insults another's mother or girlfriend and the man insulted enough is ready to flip.

He just hit on big Mike's girl.
Dude, shit's goin down.

Shit's goin down by dawg47 May 31, 2010