Once there were three bats. They lived in a cave surrounded by three castles. One night the bats made a bet to see who could drink the most blood.

The first bat comes home one night and has blood dripping off his fangs. The other two bats are amazed and asked how much blood he had drunk.

The first bat said, "See that castle over there? I drank the blood of three people." The second bat goes out on his night and comes back with blood around his mouth. The other two bats are astonished and ask how many people's blood had he drunk. The bat said, "See that castle over there. I drank the blood of five people."

The third bat goes out on his night and comes back covered in blood. This was totally amazing to the other two bats. They ask how much blood he drank. The 3rd bat said, "See that castle over there?" and the other bats nod. "Well," says the third bat, "I didn't."