Einstein and Mr Bean are sitting next to each other on a long flight.
Einstein: Let’s play a game. I will ask you a question, if you don’t know the answer you pay me only $5, and if I don’t know the answer, I will pay you $500.
Mr. Bean: OK.
Einstein: What is the distance from the earth to the moon?
Mr. Bean: *Silently hands over $5*
Einstein: All right, now it’s your turn.
Mr. Bean: What goes up a hill with four legs but comes down with only three?
Einstein: *Asks all his friends and searches the web but does not find the answer. After an hour, he finally gives Mr. Bean $500*
Mr. Bean: OK, what is your question?
Einstein: What DOES go up a hill with four legs but comes down with only three?
What happens next?