So this lawyer, as the airplane is about to take off, learns that his seat-mate is one of those computer guys, an engineer or something. The lawyer is tired, he just wants to take a nap on the plane.
The computer guys says "Hey, do you want to play a game, kind of like trivia, to pass the time?"
The lawyer explains that no, he doesn't, he just wants to take a nap.
The computer guy says "But this is really interesting: here's how it works. You ask me a question, and if I don't know the answer, I'll pay you five dollars. Then I ask you a question, and if you don't know the answer, you pay me five dollars."
The lawyer, noticing that the fellow was armed with a laptop, and really just wanting to take that nap, declined.
The computer guy then said "I'll tell you what. You ask me the question, and if I don't know, I'll pay you FIFTY dollars. If I ask you a question you don't know, you just pay me the same five dollars."
The lawyer, thinking that he's never going to get to sleep here, says "All right. What goes up the hill on three legs, and down the hill on four legs?", and then puts his head over against the window of the airplane and closes his eyes.
The computer guy thinks very hard, looks very puzzled, can't come up with the answer, looks very frustrated, and then grabs the laptop. He fires up the laptop, searches the encyclopedia on the hard drive, searches the knowledge database also installed, even searches the dictionary and the spell checker in the word processor, and can't come up with it. The geek then grabs the Airphone from out of the seat in front of him, attaches the phone to the laptop, and logs onto the internet: he searches everywhere, for an hour, and can't come up with it. He finally, very frustrated now, takes a fifty dollar bill out of his wallet, nudges the lawyer awake, and says "Here. I just don't know."
The lawyer says "Thank you", and leans his head back against the airplane window, and closes his eyes.
The geek says "Wait a minute: what DOES go up the hill on three legs, and down the hill on four legs?"
The lawyer opens his eyes, takes a five dollar bill from his pocket, hands it to the engineer, leans back against the window, and closes his eyes....