Bloody Bats

I love this joke too!

There are three vampire bats hiding in a cave surrounded by three castles. One night, they decided to have a blood-drinking contest.
The first bat went and came back with blood dripping from his fangs. The other two were amazed.
"Whoa!" Said a bat "How many peoples blood did you drink?"
"You see that castle over there?" The first bat pointed to one of the castles. the other two bats nodded "I drank blood from three people there."
The next night, the second bat went out and came back with his face covered in blood.
"See that castle over there?" She said to their bewildered expressions. "I drank blood from 5 people.
The next night, the last bat went out and came back, his whole body covered in blood.
"How much blood did you drink?"
"See that castle over there? Well, I didn't!"