A guy walking down a street one afternoon passes an old man sitting on the side of the road with a large sack.
The younger guy says to the old man, "Watcha got in the sack? "
The old man responds, "I got some monkeys in that there sack. "
The younger man asks, "If I guess how many monkeys you got in the sack, can I keep one? "
The old man replies, "Son, if you guess how many monkeys I got in this sack, I'll give you both of 'em! "