Who's Smart?

A man and a woman were sitting next to each other on the plane. The man asked the woman, "Hey, wanna play a game? Let's ask each other a question in turn. If you don't know the answer, then you give me $5, and if I don't know the answer to your question, then I'll give you $5 too."
The woman said, " I really don't want to play unless you give me a handicap. If I don't know the answer, then I'll give you $5, but if you don't know the answer, you'll give me $50. Okay?"
The man thought he was much smarter than the woman, and so he confidently agreed.
There he started, " How many moons does Jupiter have?" After a few seconds, the woman said, "I don't know." And she reached into her purse and gave the man $5.
So came the woman's turn, "What goes up the hill with two legs and comes down with three?"
Reluctant to lose, the man hastily took out his laptop and searched the internet. After half an hour, the man sighed, "I don't know." And he reached into his purse and gave the woman $50.
A few minutes later, the man couldn't help but to asked the woman slowly in a low voice, "What was the answer?"
"I don't know either." The woman reached into her purse again and gave $5 to the man.