In the Navy we refer to them as ‘brown trout’. There are a lot of important things one used to learn on warships -
1. reducing valves fail and that urinal becomes a shower; a toilet becomes an enema machine.
2. hot water comes from steam heating cold water. Never jump in a shower without turning on the water first to verify it’s not just steam.
3. pipes rattling in a head is normally due to a slug of steam making its way toward your shower nozzle. Get out fast.
I did a short training tour on a ssn. The head scared me.