A frog was hopping alongside a river bed one fine morning when he happened upon a scorpion. "Brother Frog," said the Scorpion. "Would you help me to ford the river?" But the frog with suspicion replied, "But if I carry you upon my back, then you will sting me." The Scorpion laughed. "If I were to sting you, I would then myself drown," he reasoned. Finally being convinced, the Frog allowed the the scorpion to get on his back.
About half way across the river, the Scorpion stabbed the Frog in the back with his stinger.
"Fool!" cried the Frog. "Now we will both perish!"
I've heard two variations of the story from here:
This is my favored
"Dear frog, I can swim."
The other is
"Better we should both die then I should suffer my foe to live."
The moral is the same: Some people are just dicks.