(noun phrase) anus the passage through which excrement travels, possibly derived by analogy from "trash chute;" a phrase often used to describe the anus in the context of discussions of anal sex, as in "Up the old poop chute." The variant spelling, "poopshoot," does not seem to reflect the derivation of the word
POOP CHUTE
Meaning of POOP CHUTE in English
Slang English vocab. Английский сленговый словарь. 2012