What is the policy on walking around in uniform and having music playing?

Great if you are in a parade LOL

Are you walking around with headphones in or a 90s style boombox on your shoulder????

Each svc branch has their regulation. I think even the Marines have their own directive which could be tighter than the Navy to which the Corps is. attached. Depends where you are too. The host base/Post Regs, guidelines prevails (many based these days has multiple service branches working on base/PostS. Personally keep it discreet (have rad buds that match your flesh and don’t be doing the be-bop and hauling a monster ghetto-blaster that hits 8 on the richtor scale...