Sadly neglected by her husband, a horny housewife turned to her next-door neighbour for advice. "Why don't you order your milk from the milkman" was the suggestion, "and when the bill comes, see if you can settle it with sex."
This seemed like an excellent idea, and sure enough, when the bill was presented, the milkman was delighted to settle for a long and energetic screw. Putting his pants back on, the milkman reached for the bill to mark it "Paid in Full"
In "Oh, no you don't," said the housewife, grabbing the bill. "You brought me this milk a quart at a time, and that's the way I'm gonna pay for it."