monkey jumping back to ass - unnecessary, utterly disgusting and NOT fun

monkey jumping back to that guy's ass is absolutely unnecessary, disgusting, not funny at all, and even satanic !!
The monkey jumping out of the ass is indeed funny, and the point was made. I just cannot understand the need for that later brutal act of monkey getting back to the ass, and really find Tom Shadyac's sense of humor dangerously sick there.
Because of that scene the movie definitely should have been rated with R or something, because that scene is in fact very upsetting to many of the viewers!!