GumperJumper

An inflatable jumper half-filled with mentally diagnosed retarded adults, and half-filled with conscious thinking adults, all having sex with the other, with the female partner bouncing as high up and down as they can on the male genitalia.

Morgan: Hey David, Samantha invited me to a GumperJumper tomorrow night, wanna go have sex with some normal people?
David: eughh uhhhhh ergummmm yeth David I wan go thumping with yew.