You'd be surprised at what some folks wear. One of the guys in my shop in Plattsburgh, NY wore undies very similar to these. He was happily married with children and was a "man's man" on those nights when we'd have "shop meetings" at the local bar. He was from the Bronx though, was a yankees fan, and had, well, um, all the clothes to prove it.
What anybody wears,(specially underwear) is up to his/her taste, the guy on his right is wearing silver shiny sport shoes instead of the reglamentary boots.
I guess that when bullets are flying around you you just don't pay attention to "etiquette" rules.