After you've proven how good you are, then you get to boast. They can't figure out your strategy if you don't have one. This one's my favorite. I love having my opponents think I'm clueless. It allows them to rationalize all sorts of bad behavior.
Rationalization is the act of a rational man.
Frequently we know the right thing to do, but we look for an excuse not to do it. We know, for example, that it's senseless to draw to even an open-ended straight against just one other opponent, yet we do it just the same, just to see the look on that smug bastard's face when we draw out on him. I never drink before the sun is over the yardarm, but fortunately the sun was over the yardarm yesterday. Again, people will do anything to rationalize their atavistic urges. For anyone else, one drink is too much, two drinks are ridiculous.