Instead of converting some existing files, I just found these and thought I'd post them. FYI, I do enhance the brightness and/or contrast to show off their nylon better and usually crop the original photo down.
The black dude must have slipped on some brand new nylon tricot green silkies right out of the package. They look new and super silky and big enough to hold his big black dick in them. They look a little larger than the usual shorts, but you can still they they are the Soffee 100% nylon tricot ones. That cock is being held up and a little too concealed by his inner nylon panty brief. You can see through a lot of their sheer outer nylon shorts and make out their inner briefs that's holding their goods. Check out the guy on the far left of the 2nd photo. Too bad we can't see more of him and his extra sheer outer shorts. They look so oblivious to the fact that they are standing there with dozens of other guys who are also all wearing their silky nylon tricot shorts. Of course they have checked out the other guys to see if their dicks are sticking out more than their own or if you can see their panty outline of their inner nylon brief. Even with their hands at their sides or behind their backs, they can cop a little feel of their green silkies. When not in formation, they are free to scratch their crotches, reach under their shorts to adjust their cock in their nylon panties or just rest their hands on their nylon covered hips and enjoy the feel. Unfortunately for most of them, they have to wait until they get back to their bunks after lights out to really put that silky nylon to use. Just putting another pair of green silkies under them on their bunk and fucking them or even easier to just rub one out feeling that silky nylon over their hard on is all it takes. You can be sure there are a lot of crusty chunks showing through when they get out of bed in the morning--maybe some of them are still a little wet. Doesn't matter because they can rinse them off in the shower or wear them again that day for underwear or even slip on another pair. There doesn't seem to be any regulation on what they wear for underwear--especially since the USMC issued them their nylon green silkies in the first place. It's not like they are wearing a woman's nylon panty under their nylon shorts is it? lol They're tough, macho marines after all.
I split up and enlarged the other photos so you could make out their vpls better and see how that silky nylon just drapes over their cocks and asses. For all those marines who weren't already wearing their green silkies as underwear (and often as sleepwear, too), all those other guys had to pull down their scratchy cotton briefs and slip into their nylon shorts. They looked down and saw that inner panty-like brief and watched as they pulled up their shorts over their hairy legs and their little panty rising up to hold their cock and balls inside while their outer nylon tricot short covered them up. You can be sure there wasn't one of them that didn't adjust their inner manhood and felt how silky that nylon felt on them. It's hard to imagine that any of them would ever go back to wearing their old cotton briefs after feeling how good that nylon tricot felt on them. Probably a lot of them just kept them on--we already know that a lot of marines are still wearing them as underwear even with their new issued baggier ones have to be worn for pt.