A Programmer and an Engineer are sitting next to each other on a long flight from LA to Paris. 

The Programmer leans over to the Engineer and asks if he would like to play a fun game. 

The Engineer just wants to take a nap, so he politely declines and rolls over to the window to catch a few winks. 

The Programmer 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 Engineer politely declines and tries to get to sleep. The Programmer, now somewhat exasperated, 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 the Engineer's attention, and he sees no end to this torment unless he plays, so he agrees to the game. The Programmer asks the first question. "What's the exact distance from the earth to the moon?" 

The Engineer doesn't say a word, but reaches into his wallet, pulls out a five dollar bill and hands it to the Programmer. Now, it's the Engineer's turn. He asks the Programmer "What goes up a hill with three legs, and comes down on four?" 

The Programmer looks over 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 e-mail to his co-workers -- all to no avail. After about an hour, he wakes the Engineer and hands him $50. 

The Engineer politely takes the $50 and turns away to try to get back to sleep. 

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

Without a word, the Engineer reaches into his wallet, hands the Programmer $5, and turns away to get back to sleep.