When asked "which position would you be in a human centipede?" most would answer "first." I, however, would answer third. Why you ask? When the first member of the centipede is fed, they will eventually defecate forcing the second member to ingest their feces. One could imagine that would be considered incredibly disgusting. As such, the second member would immediately vomit. After vomit travels into the first member's anus and up into their colon, they'll then pust another load into the second member's mouth even more disgusting than the last. The third member would never ingest the feces of the second member as they will always vomit what the first member expels back into them. The third member of the centipede gets to chill while the first and second trade a volley of shitty barf with each other forever.