A British firm, BCB International, is offering troops Kevlar underpants, which have several layers of Kevlar around the groin and thigh area. This protects troops from genital damage, and projectiles that might sever the femoral arteries (which run down each leg, close to the inner thigh.) Bleeding from the femoral artery is a major cause of combat deaths, as it is very difficult to stop the flow of blood.
The "blast boxers" are being sold for about $100 a pair, and the idea was suggested by the troops themselves, and the medics that treat many of these wounds. The increased number of groin injuries come largely from the growing use of roadside bombs and mines by the Taliban in Afghanistan.
There are reasons why troops might not want to use the Kevlar undershorts. For one thing, they restrict movement a bit, and are hot when worn during warm weather. The mobility issue discouraged U.S. Marines from using a Kevlar flap that was added to their protective vest, to prevent groin injuries.
But there are a lot of troops who would probably find these two issues as non-problems. These are the guys who drive the roads of Afghanistan, delivering supplies, or aid to Afghans, or just searching for roadside bombs. Mobility on foot or heat is not what these vehicle bound troops are concerned with, but the impact of roadside bombs or ambusher's bullets is. This may be the primary market for the hundred dollar shorts.