Cunt Soap

Soap used to sanitize the vagina just like a douche, hence it can readily be interchanged with the terms douche or douchebag It is a much more vulgar way of referring to an individual deemed unpleasant, idiotic, and generally annoying in all possible ways.

Boyfriend: "You're sister's new boyfriend is a douche!"
Girlfriend: "Don't call him that; it's mean!"
Boyriend: "Oh sorry...you're sister's new boyfriend is a piece of cunt soap!"
Girlfriend: "I'm leaving you..."