2 guys, 1 chick in the middle. One guy puts his balls next to her left ear, and the other on the opposite ear. The two guys rock, paper, scissors on who goes first. The guy who goes first lets his balls hang then lets go, hitting the chicks ear. Then the energy is transferred due to elastic collision.
Bruh, me and my homeboy Tony fucked this chic. We did the Newton's cradle and she ended up with a concussions.
The action of 2 men standing next to one another and swinging their balls in such a way that they swing back and forth due to the horizontal force of each set of balls making direct contact
When in an act of a 3-some involved with a female and two males and one penis is in the ass and one penis is in the vagina and their balls are alternating turns clanking together with their momentum.