Mr. Bean v/s Einstein

Einstein & Mr.Bean sitting next to each other
on a long flight..

Einstein says, 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..

Einstein asks the first question :

What's the
distance from the Earth to the Moon..?

Mr.Bean doesn't say a word, reaches his
pocket, pulls out a $5..

Now, it's Mr.Bean's turn..

He asks Einstein : What goes up a hill with 3
legs and comes down on 4 legs..?

Einstein searches the net and asks all his
smart friends..

After an hour he gives Mr.Bean $500..

Einstein going nuts and asks :

Well,so what
goes up a hill with three legs and comes
down with four..?

Mr.Bean reaches his pocket and gives Einstein
5$