The always fascinating Recomendo suggests some quick-refreshing underpants:
Travel underwear. These very lightweight, super quick-drying, comfortable briefs are made of a blended material with a new finish that is unusually resistant to the growth of bacteria. You wash them in cold water in your hotel room at night and they are dry before morning. In a pinch, they can be dry in a couple hours if you roll them in a towel and squeeze the water out before you hang them up. I reused one pair of underwear three times on a recent trip.
Fortunately, they also come in more stylish boxers or boxer briefs. I particularly like the endorsement from the Eco Challenge team.