Rhuby has always been partial to Royal Naval slang.
Some American examples:
Signalman: Skivvie Waver. Skivvies are underpants.
Machinist's Mate: Mickey Mouse. The abbreviation is MM and the symbol worn on the uniform is a three bladed ship's propeller that looks like a Mickey Mouse head.
Hospital Corpsman: Aviation Snake Charmer. The symbols worn on the uniform for aviation ratings usually were the equivalent of the non-aviation version with the addition of wings. Electronics techs had a helium atom, avaition electronics techs had a winged helium atom. The hospital corpsman symbol was a caduceus.
Boatswain's Mate: Deck Ape. Also a generic term to indicate someone not a snipe, a seabee or an Airedale (q.v.)
General term for ratings that worked on the machinery of the ship: Snipe. This included the classic snipe ratings; Machinist's Mate, Engineman, etc. and also Electrican's Mate.
Electronics Technician: Super Snipe. It was originally a snipe rating before it became a deck ape rating.
Aviation anything: Airedale. Also Brown Shoe (no rational reason for this one)
Constructionman: Seabee. These were the guys that left notes behind on the beaches after they prepped them for the Marine landing forces in the Pacific in WWII.