One day a man walks into a dentist's and asks how much it will cost to extract wisdom teeth?

One day a man walks into a dentist's and asks how much it will cost to extract wisdom teeth? $160, the dentist says. That's a ridiculous amount, the man says. Isn't there a cheaper way? Well, the dentist says, if you don't use an anaesthetic, I can knock it down to $120. That's still too expensive, the man says. Okay, says the dentist. If I save on anaesthesia and simply rip the teeth out with a pair of pliers, I could get away with charging $40. Nope, moans the man, it's still too much. Hmm, says the dentist, scratching his head. If I let one of my students do it for the experience, I suppose I could charge you just $20. Marvellous, says the man, book my wife for next Tuesday !