Jolly Roger
There is a strange custom in the Royal Navy that allows submarine commanders to fly the jolly roger (a pirate’s flag) whenever they return to port. This tradition has its origins in the 1900s.
Unfair, underhanded, and dishonorable; that’s how Sir Arthur Wilson, the First Sea Lord of the British Navy, saw submarines. Nonetheless, when the first British submarine sank a German U-boat during WWI with a torpedo strike ordered its captain to have his crew make a jolly roger, which was then flown from the mast.