girl's ass Share definition Flag The back side of a girl. It is used for spanking, humping, and twerking. Men find pleasure in the ass. it a great way to attract men. Dude look at that girl's ass it's so big. girl's ass by Savagegroot March 22, 2017 0 0 Get merch Get the girl's ass mug. Buy Now — $32.95 See more merch