[Aaron W.]

I'll bet all the ones where it's heads up and villain checks to me. If he folds 33% of the time, you win automatically (plus the times that he calls you sometimes have the best hand, or draw to the best hand, or make him fold on the turn). If it stays heads up for more than 10-15 hands or so, he might catch on and start calling you down with junk, even if you start checking behind and value betting. Or he may turn into a hyper-bluffer himself, which is generally an awesome thing.