An Indian man and Einstein

Are on a flight, Einstein makes a bet with the man sitting next to him.
"I will give you 500 dollars if you can ask me a question I don't know the answer to,however, if you cannot answer my question you must give me 5 bucks."
The man thinks it about 5:500 seems like a good ratio so he says sure.

Einstein asks what is the exact distance between Earth and the moon?

The man replies I don't know, so he hands over 5 dollars. It is then the Indian mans turn to ask Einstein a question. He asks "what goes up a hill with 4 legs and comes down with three?"

Einstein thinks and thinks and finally hands over 500 dollars. He asks "before my next question what does go up a hill with 4 leg and come down with 3?"
The Indian man gives Einstein another 5 dollars.