A monkey goes to a bar

A man walks into a bar and orders a beer. He takes his first sip and sets it down. While he is looking around the bar, a monkey swings down and steals the pint of beer from him before he is able to stop the monkey.

The man asks the barman who owns the monkey. The barman replies the piano player. The man walks over to the piano player and says "Do you know your monkey stole my beer." The pianist replies "No, but if you hum it, I'll play it."