When asked "which position would you be in a human centipede?" most would answer "first." I, however would answer third. Why you ask?
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.

𝓜𝔂 𝓭𝓮𝓪𝓻𝓮𝓼𝓽 𝓫𝓻𝓸𝓽𝓱𝓮𝓻, 𝓽𝓸𝓭𝓪𝔂 𝓶𝓪𝓻𝓴𝓼 𝓽𝓱𝓮 8𝓽𝓱 𝔂𝓮𝓪𝓻 𝔀𝓮 𝓱𝓪𝓿𝓮 𝓱𝓪𝓭 𝔀𝓲𝓽𝓱𝓸𝓾𝓽 𝓿𝓪𝓻𝓲𝓮𝓽𝔂. 𝓦𝓮 𝓶𝓪𝔂 𝓷𝓸𝓽 𝓫𝓮 𝓪𝓫𝓵𝓮 𝓽𝓸 𝓮𝓷𝓭𝓾𝓻𝓮. 𝓟𝓵𝓮𝓪𝓼𝓮 𝓹𝓻𝓪𝔂 𝓯𝓸𝓻 𝓸𝓾𝓻 𝓼𝓪𝓵𝓿𝓪𝓽𝓲𝓸𝓷. .