The first thing I did when I got these was strip down to my birthday suit and slide these bad boys over my legs.  The soft nylon is a perfect material for underwear.  Why is it so hard to find?!  Cotton is the worst, and you'll be saying it with me when you try these on.  Anyway, the have really nice support for "your boys," which comes in handy for bike riding and other activities.  The odor resistance is awesome too - the actually don't stink after a 4.5 mile bike ride!  And washing is awesome - just rinse with a little soap, and hang dry - they will dry in an hour or too, and you'll be ready to glide them over your leg-hairs once more!

The one minor con is that they have a lot less friction than cotton, so if you wear loose pants and bend over, you can almost be sure that your underwear will do everything in its frictionless power to escape the confines of your Levi's.  This is minor though - wear a belt.