This phenomenon enables you to tag her from behind, allowing your balls to swing freely between her legs without touching them, tapping the front of her, like the famed executive ball clicker --- the Newton's Cradle.
She was in really good shape, a total Newton's Cradle.
--I did the Newtons cradle on those bitches tits.
Adam: "Nah, me and Pete did that and my balls ache."
Pete: "Awww yuh."