The Dangers in Watermelon Farming

There was a farmer who grew watermelons. He was doing pretty well,
but he was disturbed by some local kids who would sneak into his
watermelon patch at night and eat his watermelons. After some
careful thought, he came up with a clever idea that he thought would
scare the kids away for sure.

He made up a sign and posted it in the field. The next day, the kids
show up and they saw the sign which read: "Warning! One of the
watermelons in this field has been injected with poison."

The kids ran off, made up their own sign and posted it next to the
farmer's sign. When the farmer returned, he surveyed the field. He
noticed that no watermelons are missing, but the sign next to his
read: "Now there are two!"