A girl walks into a bar with a Monkey.
The bartender freaks out "HEY! you can't bring a monkey in here! Get it out!"
The girl pleads with the bartender, that she's trying to socialize the monkey, and he won't be any trouble and she just wants one beer.
The bartender finally gives up, and besides she is quite pretty.
As soon as he serves the girl the beer the monkey starts running up and down the bar, knocking over drinks, breaking glasses and being a general nuisance. Before the girl can catch him, the Monkey jumps on the pool table and swallows the cue ball.
The girl apologizes profusely and pays for the damage, collects the Monkey and leaves.
A few weeks later she shows up again, with the Monkey.
The bartender freaks out "HEY! GET THAT MONKEY OUT OF HERE!"
The girl pleads again with him, and once again the bartender relents; She is even prettier than he remembers and he is after all an optimist. Once again, as soon as he serves the girl her beer the Monkey proceeds to tear up the bar, knocking over drinks, breaking glasses and screaming at patrons. Eventually the Monkey finds the garnish tray, grabs a maraschino cherry, sticks it in his butt, then eats it.
Not only the bartender, but every patron is totally grossed out by this behavior.
The bartender says to the girl "that's the grossest thing I've ever seen; you get that beast out of here right the fuck now!"
The girl apologizes and proceeds to leave but she is compelled to explain the Monkey's behavior.
"He really isn't a bad Monkey. You see, since the last time he was in here he measures everything he eats first."