To chill or stand at a spot (like a club or a street corner etc). To claim a spot. The term came from drug dealers on street corners, like light posts and street posts, and there you have it POST UP!
nigga1: "can u kick it right now?"
nigga2: "naw, can't u see I'm posted+up? maybe later nigga"
By Mada
Post Up
To incite a fight, or to call someone out.
used when people are mad and desire confrontation.
Girl:(Greg) Dude you look like Justin Beiber!
Greg:awh, thanks,(:
Jim: Greg, what a fag,
Greg:Post Up then bitch!
By Demeter
Post Up
Basketball term where a big man like Shaq goes down low (near the basket, establishes a good position, pins his man with his body and asks for the ball.