Sexual position in which three or more people assemble single file, on all fours and place their faces in the person in front's butt cheeks. Each person in the chain then proceeds to deficate into the following person's mouth, with the last person ending the chain with their's falling to the floor.
Thus completing the Human Centipede.
Guy #1: Bro, picked up two hookers the other day and they asked me to be The human Centipede head.
Guy #2: What the fuck?! Did you do it?
Guy #1: ...