The Telegraph has a fascinating article about how slang from the trench warfare of World War I entered common English usage, and persists to this day. Here's an excerpt.
If you’re feeling washed out, fed up or downright lousy, World War One is to blame.
New research has shown how the conflict meant that hundreds of words and phrases came into common parlance thanks to the trenches.
. . .
The results of the research are included in a new book, Trench Talk: Words of the First World War, which documents how new words and phrases originated, while others were spread from an earlier, narrow context, to gain new, wider meanings.
Many of the words were created by soldiers to describe their unfamiliar surroundings and circumstances. While they had to come up with names for new items like “trench coats” and “duckboards”, other, more descriptive phrases were also developed.
“Lousy” and “crummy” both referred to being infested with lice, while “fed up” emerged as a widespread expression of weariness among the men.
. . .
Other phrases to develop were “snapshot” (from a quickly aimed and taken rifle shot), and “wash out”, which described a process by which aspiring officers who failed their commissions and were sent back to their regiments, or “washed out”. By 1915 the term was being used to signify any kind of failure.
“Dud” also came to take on a wider meaning for something which failed, from the large number of faulty shells which did not explode.
. . .
Many more new terms came from the mix of nationalities thrown together by the war.
The French term souvenir replaced keepsake as the primary word for a memento, following exchanges with the locals, while officers being sacked were said to have “come ungummed” - from the French “dégommér”, to dismiss. This quickly developed into “come unstuck”.
Other words arrived with troops from the US - such as “cooler”, for prison - and Canada - including “swipe”, for acquiring something by means that were not necessarily above board.
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Many of the technical devices encountered by soldiers could be quite baffling and hard to describe, which helps to explain the widespread emergence of the word “thingumyjig” from the period.
There's more at the link.
Of course, I'm familiar with many of these words due to my background of English parents and a colonial upbringing. Americans may find some of them less familiar. Nevertheless, the article makes interesting reading.