Two people are sitting next to each other on the long flight from LA to NY. One leans over to the other and asks if he would like to play a fun game, but the other says he'd rather just take a nap, and politely declines and rolls over to the window to catch a few winks.

The first persists and explains that the game is real easy and a lotta fun. He explains "I ask you a question, and if you don't know the answer, you pay me $5. Then you ask me a question, and if I don't know the answer, I'll pay you $5. Again, the other person politely declines and tries to get to sleep.

The first person, now somewhat agitated, says, "OK, if you don't know the answer you pay me $5, and if I don't know the answer, I'll pay you $50!"

This catches his attention, and he sees no end to this torment unless he plays, so he agrees to the game. The first person asks the first question. "What is the distance from the earth to the moon?"

The other doesn't say a word, but reaches into his wallet, pulls out a five dollar bill and hands it to the guy.

Now, it's the his turn. He asks the first person "What goes up a hill with three legs, and comes down on four?"

The first looks at him with a puzzled look. He takes out his laptop computer and searches all of his references. He taps into the Airphone with his modem and searches the net and the Library of Congress. Frustrated, he sends email to his co-workers -- all to no avail.

After about an hour, he wakes the guy and hands him $50. He politely takes the $50 and turns away to try to get back to sleep.

The first, more than a little miffed, shakes the guy and asks "Well, so what's the answer?"