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 anaesthetic,
I can knock the price down to £60."

"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 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."

"Marvellous," says the man, "book my wife for next Tuesday!"