Definitions by katiegurl19512

under butt 

n. the cleavage at the bottom of ur butt and top of ur leg. Usually on girls with bigger butts. Also known as under tuck.

Guy 1: Damn! do u see that chick over there? shes got a nice ass!
Guy 2: Yeah shes got a nice under butt too!

under butt by katiegurl19512 October 23, 2009