A crude sexual act. It involves a male hiding in a closet, under the bed, on the ceiling fan, etc. while wearing a mask. When a woman (or man if you prefer) walks into the room, the male comes out of hiding and situates themself so that they may ejaculate into the unwary victim's face. You then yell, "SURPRISE BITCH" and run out of the room. For a better effect run naked.
"SURPRISE BITCH, EAT THAT SEMEN SURPRISE!"