Nimble blonde

The lawyer invites the girl to play a simple game - so that it is not boring. The blonde refuses - she is tired and wants to sleep. The lawyer insists on the game: - You will see, it's quite simple. I ask you a question, if you don't know the answer, you pay me $ 5 and vice versa. She refuses again.

“Okay, ” says the lawyer. - Let's change the rules: if I cannot answer your question, I will pay you $ 500; on the contrary, you are only 5 to me.

Then the girl agrees. The lawyer asks her how many kilometers are between the Earth and the Moon. Silently she takes out 5 dollars, gives him and asks in turn:

- What goes uphill on three legs and back down on four?

The lawyer thinks for a long time, takes his laptop, tries to find something useful on the Internet, then calls his friends - all in vain. Two hours later, he wakes up the blonde and gives her 500 bucks. She takes them and settles down to sleep again. He pushes her aside and asks:

- And what is the answer? She silently takes her bag, gives the lawyer $ 5, and falls asleep.