I would like to hear from some people who have used their knowledge of the game and its rules in a match (i.e. using a rule that most people don't know about in your favor). For example, in one match a while ago, after hitting my first serve, a ball from a neighboring court rolled near me. I hit the ball back and called a let (by the rule stating that any interruption between first and second serves results in a let). My opponents thought I was crazy and called their coach over, only to have him confirm that I was right to call a let. It was quite amusing since they thought I was making things up. It's always fun to get at your opponents that way and show that you know the game.