It's always handy for one's underwears to be flame-resistant and anti-static, but now the Japanese have invented underwear that does all that and takes it a few steps further: it's anti-bacterial, anti-odor, and can be worn for more than a week straight.
But, um, why would anyone want to? What's the practical purpose for this?
Astronauts-- and, on a more applicable level for non-astronauts, travel. Koichii Wakata, who has been testing these drawers out, is the first Japanese astronaut living on the International Space Station, which has no laundry facilities. And taking baggage into space is expensive, so you can see how extended-wear underwear would be useful.
Still, we're not quite sold. Maybe the underwear wouldn't smell, butt but...
Related:
Why You're Always Adjusting Your Boobs: A Look at Modern Underwear