The Scorpion and the Frog
One day a scorpion was walking around, looking for houses to invade and toes to sting, when he came upon a river. Scorpions are unable to swim, so he asked a nearby frog to carry him across.
"Why should I help you?" asked the frog. "You are a scorpion. Your sting will kill me."
"I promise not to sting you," replied the scorpion. "After all, if I sting you we'll both drown."
The frog agreed to carry the scorpion across, and the scorpion crawled onto the frog's back. Half way across the river the scorpion stung the frog in the neck. The frog kicked a few times, but then began to sink as the poison took its affect.
"Why did you do that!?!?" screamed the frog. "Now we'll both drown!"
"It is in my nature," said the scorpion.
Moral of the story: Scorpions are assholes.