When two men are having intercourse with the same woman, one man is in the Vagina, and the other in the anus. While they are thrusting their hips, their balls hit or rub against each others.
Boy1: Bro, what happened last night?
Boy2: I don't know?
Girl1: I'll give you boys A hint, you two played BumperBalls on me all last night.
Boy2: I don't know?
Girl1: I'll give you boys A hint, you two played BumperBalls on me all last night.
by OfficerChip November 21, 2011
by CoOl DaDdy PiMp MaStEr April 03, 2006