During the act of two men penetrating a single orifice of another person, their testicles collide causing a swinging effect similar to that of newton's cradle, the device used to display preservation of energy.

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.

hip thrust x ball mass = good times squared

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.

While in the Doggy Style Position, slap her tits as to mimic the Balls of a Physics toy known as a Newtons Cradle