One day, a woman 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 woman 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," replies the woman. "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 woman, "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 woman. "May I book my mother-in-law for next Tuesday please?"