Jamaican Jackhammer

A sexual act involving 4 people. A man gets his legs held above him by two (2) people and held apart, in a "V" shape. A fourth person is then helped in between the man's legs and his balls are then used as a trampoline until he cums.

Mike: Yo, Steven. I heard that Stacey gave you the Jamaican Jackhammer last weekend
Steven: Yes mate, I've been in intensive care cos Kate and her sister held my legs open and Stacey weighs 250kg