That's where there's a guy on the bottom fucking a girl in the ass and there's a guy on top fucking her in the vagina creating a triple decker sex-sandwich thus wrecking their peckers.

When three males have a threesome and they sit ontop of each other at the same time.

Sex move: when three men are having a threesome and the guy on the bottom is giving anal, the guy in the middle is receiving AND giving anal, and the guy on top is getting anal while his dick/her strap-on flops about like an epileptic fish.