One man holds a stick between his legs, acting as his sexual organ, while the other is bent over with the stick, or long objects positioned up his ass. The mimicked act is usually accompanied by loud, obnoxious moaning by the participants in order to deliver as much shock value to the terrified on-looker(s) as possible.
Onlookers are typically suburban homeowners, who have had their doorbells rung, only to find the ball-banging taking place on their lawn, porch, etc. Common ball-banging grounds also included restaurants, malls, or other crowded areas.
Origin: Invented in Upstate, NY by a group of teenagers