Set up a video camera and then do what jerkasaur said, because it would be hilarious to see just how much that would fail. When I was in my teens I used to use the wrestling trick. You start roughhousing and get into a situation where you're trying to pin each other, and you can tell she's actually trying. And then you let her pin you. And while you're both laying on the floor panting and sweating, you look into her eyes, and you kiss her. I don't think I ever had it fail.