A guy walks into a bar with his pet monkey. He orders a drink, and while he's drinking, the monkey jumps all over the place, eating everything behind the bar. Then the monkey jumps on to the pool table and swallows a billiard ball.
The bartender screams at the guy, "Your monkey just ate the cue ball off my pool table -- whole!"
"Sorry," replied the guy. "He eats everything in sight, the little bastard. I'll pay for everything."
The man finishes his drink, pays and leaves.
Two weeks later, he's in the bar with his pet monkey, again. He orders a drink, and the monkey starts running around the bar. The monkey finds a maraschino cherry on the bar. He grabs it, sticks it up his but, pulls it out and eats it.
The bartender is disgusted. "Did you see what your monkey did now?" he asks.
"Yeah," replies the guy. "He still eats everything in sight, but ever since he swallowed that cue ball, he measures stuff first."