A guy walks into a bar with a monkey on his shoulder. The guy sits at the bar, and starts talking to the bartender. While they're talking, the monkey walks over to the pool table, and eats one of the pool balls.
The bartender says to the guy, "What's wrong with your monkey? He just ate one of the pool balls!"
The guy replies, "I can't help it. He eats anything and everything, and there doesn't seem to be a thing I can do to stop it." He then picks up the monkey, and leaves.
A few days later, the guy shows up at the bar and again, he's got the monkey with him. This time, the monkey sits down at the bar, grabs a peanut from a dish, sticks it up his butt, then pulls it back out and eats it.
The bartender says to the guy, "What the heck is he doing now?" The guy answers, "He still pretty much eats everything, but after the ball incident a few days ago, he checks to make sure it will fit before he eats it."