pump the chemical toilet

When one has sexual intercourse with a less than desirable looking female, usually a 'sex worker' aka whore.

Origin: Family Guy

Quagmire (with a trashy girl on his arm): Hang around little guy, I'll be back later (he winks).
Stewie: Oh very well. I suppose I'll go and pump the chemical toilet. (Eyes the trashy girl.) apparently, you're about to do the same.