A guy walks into a piano bar, sits down and orders

A guy walks into a piano bar, sits down and orders a beer. He notices a little monkey is sitting on the piano. He holds up a dollar and the monkey hops over and snatches it out of his hand and puts it in a tip jar and sits down again. He does it a couple more times, tickled seeing the monkey's antics. After a few beers he has to go to the bathroom. On his way back he sees the monkey with his hind leg perched over his beer. He shoos him away and says to the piano player, "Hey, do you know your monkey peed in my beer?' The piano player replies, "No, but if you hum a few bars I'll try to follow you."