One Man's Pornography

I may have told this before, but it's worth repeating. An astronaut journeys to a distant planet in another galaxy and discovers an advanced and friendly civilization. After a welcome, he is given a tour, which includes a visit to a factory-like structure. He is shown a conveyor belt where tiny body parts are being assembled into living, miniature versions of the natives, and is told it's how they make babies. Astonished, he tells them how babies are made back on his home planet of earth. The natives begin to howl with laughter. "What's so funny?" he asks. "That," they tell him, "is exactly how we make cars."