One day, a man walks into a dentist's office and asks how much it
 will cost to extract wisdom teeth.
 
 "Eighty dollars," 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 anesthetic, I can
 knock the price down to $60."
 
 "That's still too expensive," the man says.
 
 "Okay," says the dentist. "If I save on anesthesia and simply rip
 the teeth out with a pair of pliers, I can knock the price down to
 $20."
 
 "Nope," moans the man, "it's still too much."
 
 "Well," says the dentist, scratching his head, "if I let one of my
 students do it, I suppose I can knock the price down to $10."
 
 "Marvelous," says the man, "book my wife for next Tuesday!"