A guy walks into a bar with his pet monkey. He orders a drink and while he's drinking, the monkey starts jumping all over the place. The monkey grabs some olives off the bar and eats them, then grabs some sliced limes and eats them, then jumps up on the pool table, grabs the cue ball, sticks it in his mouth and swallows it whole.
The bartender screams at the guy, "Did you see what your monkey just did?" The guy says, "No, what?" "He just ate the cue ball off my pool table - whole!" says the bartender. "Yeah, that doesn't surprise me," replies the patron. "He eats everything in sight, the little twerp. I'll pay for the cue ball and stuff." He finishes his drink, pays his bill, and leaves. Two weeks later he's in the bar again, and he has his monkey with him. He orders a drink and the monkey starts running around the bar again.
While the man is drinking, the monkey finds a maraschino cherry on the bar. He grabs it, sticks it up his butt, pulls it out, and eats it. The bartender is disgusted. "Did you see what your monkey did now?" "Now what?" asks the patron. "Well, he stuck a maraschino cherry up his butt, then pulled it out and ate it!" says the barkeeper.
"Yeah, that doesn't surprise me," replies the patron. "He still eats everything in sight, but ever since he ate that damn cue ball he measures everything first!"