ok, this is not "cool" to talk about, but I am having serious problems with underwear when I play tennis. I have been wearing some "calvin klein" sports boxers that are made out of a poly material. They are usually ok, but if it is really humid and I sweat a lot, I end up with serious chaffing on my legs where the seam on the underwear must rub. It hurts pretty bad and I have to walk funny just to keep from irritating it more. If I get home and put a bunch of baby powder on it.. it is usually better by morning. So, I bought some NIKE PRO undies that have a lot of spandex and are extremely tight fitting. Feels good except when I get an hour into a match the legs start riding up and I have to adjust them every point. This is more annoying than the chaffing bumps while I am playing. (but chaffing is obviously worse after...) So, I bought some Nike "running shorts" that have an internal "gusset", and have been just using those in lieu of undies. Guess what, no problems in the heat. I saw a few Nike tennis shorts have a "gusset", but they are usually really short. (7" length) Anyway, I thought I would share my very personal experience with underwear and hope it either helps somebody, or that some other players in humid weather can provide me with some tips for playing 3+ hours without discomfort in the nether region!