Anyone ever try the old negotiating technique of crossing arms when someome's saying something you don't like/want to hear and then uncrossing them when they start to concede a point? Some people (as in poor negotiators) unconsciously begin to make concessions in order to get you to uncross your arms and make them feel comfortable again. Try it some time.
Something I wish I knew as a teen/20-something is that if a member of the opposite sex touches you - in any casual context - that means they really really like you (as in would be happy to roll in the hay). True 100% of the time? No, but close enough to use as a guide whether or not to make the play.