Einstein said to Mr. Bean: “I’ll ask you a question.​If you can’t answer correctly, you’ll give me one dollar. Then you ask me a question. If I can’t answer correctly, I’ll give you 1000 dollars.
Einstein: asks a question.
Mr. Bean after a little while: gives Einstein one dollar.
Einstein says: Okay, it’s your turn.
Mr. Bean asks: What’s an animal that has four legs, but when it’s crossing a street, it has three legs and when it’s on the other side of the street, it has only two?
Einstein: Thinks hard for a while.
Einstein says: I give up. Gives 1000 dollars to Mr. Bean
Einstein asks: What is it?
Mr. Bean: gives a dollar to Einstein.