There's a story, no idea if it's true, and nobody knows who really said it first (if ever). One variant below with Groucho Marx...
GROUCHO (to woman seated next to him at an elegant dinner party): Would you sleep with me for ten million dollars?
WOMAN (giggles and responds): Oh, Groucho, of course I would.
GROUCHO; How about doing it for fifteen dollars?
WOMAN (indignant): Why, what do you think I am?
GROUCHO: That’s already been established. Now we’re just haggling about the price.