A guy walks into a bar with his pet monkey, sits down and orders a drink. Shortly after, the monkey starts jumping all over the place and acting crazy. The monkey grabs some olives off the bar and eats them... 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?" "No, what?" says the guy. "He just ate the cue ball off my pool table - whole!" says the bartender. "Yeah, that doesn't surprise me, he eats everything in sight. Quite an appetite. I'll pay for the cue ball and other things he ate." He the finishes his drink, pays the bill, and leaves. Two weeks later he's back at the same bar again, monkey by his side as usual. 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?" "What this time?" asks the patron. "Well, he stuck a 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 it first!"