When someone looks extremely attractive. This term could be specifically used for music as well. Hell, I guess it could be used for anything, really.
Big Peen: Hey, you see that guy over there?
Lil' Peen: Yeah, what about him?
Big Peen: No homo, but he lookin' mad pretty
*Riot Van starts playing*
Big Peen: Woah, this song sounds mad pretty...