I'd poop on it

When you see a girl who you are attracted to, and you say "I'd poop on it", you are saying "it" referring to her as a sexual item, rather than person, and that if you were to be given the opportunity to have sex with her, and she was into strange things like being pooped on, that she is so hot you would do it.

A phrase used to say you would have kinky sexual intercourse with someone.