Sex Ghost (1987)

The famed super naturalist Professor Probe holds a private séance with the able-bodied assistance of his choicest "A-for-a-lay" students. While engaging in the kinkiest of primal, horizontal, soul-cleansing ceremonies, Probe inadvertently succeeds in the summoning of the Spirit of Sex - a playful spectre who enters his playmates at will, possessing them and making them do the nastiest deeds without the burden of their normal inhibitions.