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.