basicaly, a slut, who either lives in a butt, or likes up the butt. can refer to homesexuals.
related to slut and skank
A. Yeah, that buttslut smells likearse. Probably because she lives in one.
B. Damn, bitch, you like it up the rear, just like my old buttslut.
C. Buttslut is another cool word for skank. :O