A man walks into a bar and orders a beer

The bartender places the beer down, but before the man can grab the beer, a monkey runs over and dips its nuts in the beer. The man is confused, so he orders another. Unfortunately, the same thing happens again. After the 4th time, he follows the monkey back to a piano where the piano player, presumably the owner, is playing.

"Excuse me sir, do you know your monkey is dipping its testicles in my beer?"

"No," replied the pianist, "but if you hum a few lines, I can fake it!"