A blonde joke

Don't worry - it's not mean.

A lawyer and a blonde woman are sitting next to each other on a long flight. The lawyer asks if she would like to play a fun game. The blonde is tired and just wants to take a nap, so she politely declines and tries to catch a few winks. The lawyer persists, saying that the game is a lot of fun.
'I ask you a question, and if you don't know the answer, you pay me only £5; you ask me one, and if I don't know the answer, I will pay you £500.'
This catches the blonde's attention; and, to keep him quiet, she agrees to play the game. The lawyer asks the first question.
'What's the distance from the earth to the moon?
'The blonde doesn't say a word, reaches in to her purse, pulls out a fiver, and hands it to the lawyer.
Now, it's the blonde's turn.
She asks the lawyer, 'What goes up a hill with three legs, and comes down with four?'
The lawyer uses his laptop, searches all references. He uses the Air phone; he searches the Net and even the Library of Congress. He sends e-mails to all the smart friends he knows, all to no avail. After one hour of searching he finally gives up. He wakes up the blonde and hands her £500. The blonde takes the £500 and goes back to sleep.
The lawyer is going nuts not knowing the answer. He wakes her up and asks, 'Well, so what goes up a hill with three legs and comes down with four?' The blonde reaches into her purse, hands the lawyer £5 and goes back to sleep.