One day while doing door-to-door market research, this guy knocks on a door and is greeted by a beautiful young housewife. Hello, he starts, Im doing some research for a petroleum jelly manufacturer. Have you ever used the product? Yes. My husband and I use it during sex, she answers. The researcher is taken aback. Um, er, I admire you for your honesty, he continues. Can you tell me exactly how you use it? Sure, we put it on the doorknob so the kids cant get in.