Farmer and the WaterMelons

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

So he made up a sign and posted it in the field. The next day, the kids show up and they see a sign saying "Warning! One of the watermelons in this field has been injected with cyanide."

So the kids run off and make up their own sign and post it next to the farmer's sign. The farmer shows up the next week and looks over the field. He notices that no watermelons are missing, but reads the
sign next to his : "Now there are two!!!"