When you are at a sauna after working out and you are naked and start rocking hips side to side as to hit their balls together.
Guy 1: Dude I was at the gym and some guy was playing Newton Balls next to me.
Guy 2: Ewwww.
When a man's two testicle collide within the scrotum resulting in a painful feeling. Much like that desk toy with the swinging balls.
Why'd you stop running?
I have Newton Balls