When you use underwear (preferably clean boxers) as an emergency MASK. You put your head in the waistband and through one leg, allowing the material to cover your leg. You put the other leg, bottom first over the top you your head. Fold the waistband under and you are done and protected.
A "Dirty Commando Shield" would be in an extreme emergency situation when you are forced to remove your underwear and use it as a mask as described above.
I tried to go to the store but they wouldn't let me in without a mask, so I returned to the car and put on my commando shield.
The name of the anime series starring a boy who meets a guy named Masarusan, who has a fighting style called, "The Sexy Commando".
To do the Sexy Commando, Masarusan unzips his pants (That's right kiddies) to distract the opponent. Then, he goes at them, violently attacking them with his fist. Sometimes he likes to gross his opponent out by having pigeons fly out of his pants.