A Scorpion begged a Frog to carry him across the river because he could not swim. The Frog hesitated for fearing being stung by the Scorpion.
The Scorpion said: “Do not worry, you know I won’t sting you since we will both get drowned if I do that”.
So the Frog carried the Scorpion across the river.
But in the middle of the river, it happened – the Frog got a sting.
Before he died, the Frog asked the Scorpion in disbelief: “I do not understand why you did this!?”
“Because I am not a game theorist and you are”, replied the Scorpion.