Isa 20:2 At the same time spake the LORD by Isaiah the son of Amoz, saying, Go and loose the sackcloth from off thy loins, and put off thy shoe from thy foot. And he did so, walking naked and barefoot.
3 And the LORD said, Like as my servant Isaiah hath walked naked and barefoot three years for a sign and wonder upon Egypt and upon Ethiopia;
4 So shall the king of Assyria lead away the Egyptians prisoners, and the Ethiopians captives, young and old, naked and barefoot, even with their buttocks uncovered, to the shame of Egypt.
Walking around without your outer garment in that day was considered being naked. i don't suspect many of our sports wear and swim suits would have been considered modest. In fact, much of what we wear would be immodest by OT and NT standards or even the standards of 60 years ago or so,
Those taken captive would be showing their buttocks. Scholars debate if Isaiah was just in his undergarments or actually naked. I think they feel God would not embarrass Isaiah like that. If he was to be a sign and wonder, he may well have been naked. A man walking in his underwear would attract attention, but a naked one more-so.
God does sometimes require His people, especially prophets. to do some things that we would consider embarrassing. When you are a dignitary for God your dignity may have to be put aside to accomplish your calling. Are you willing to be undignified to be His dignitary? I don't think He will ask you to walk naked, but if He did would you do it?