soooo someone on birdsite made a joke about Roman underpants and I went looking
apparently these are "subligaculuae" (sing subligaculum). Basically leather flaps you tie up at the hips and boom, underwear. Apparently since lower class people wore 'em, it was a pretension to go commando. Apparently one senatorial family made a big deal of showing up in toga and underpants to prove that they were full of traditional values or w/e.