Here goes.....
So this guy goes to a whorehouse and asks the madam for the nastiest girl there. She directs him to the proper room and he goes in and asks the girl how much it would be if she would lie on the ground so he can s**t on her chest? She says $25. He says OK and thats just what they do.
A few weeks later same story. This time the guy squats down and can only fart. She looks up at him and says "What's the matter, don't you love me any more?"