During the Cold War, in Germany, our Naval exchange junior officer, obviously tired of tank and aircraft recce photos, decided to give us some "alternative" lessons after morning brief.
A photo slide of the first ship went up; no-one had a clue what it might be.
From the rear came a grumpy Scottish QHI's voice (that of the late George Blackie): "That's a B Zero Eighty!"
"No", said the the NEO, "It's actually a Warsaw Pact Blah Class Blah, blah".
Next slide...totally different photo, no-one knew its ID. Same voice "That's another B Zero Eighty!"
"No, that one's a Blah Class Blah Blah....
......and what exactly is this B Zero Eighty, George?
GB stood up, walked to the front, picked up some chalk and wrote "B.O.A.T." on the blackboard, bid us good morning, and walked out.
Rude, but GB made the point well. There were no ships in our operating theatre (the Central German Plain) and we went nowhere near the coast.