A 1917 article from the the Washington Post reproduced by etymolog (the link goes to his promising new blog) in this Wordorigins thread sheds light on the new slang created or popularized by British soldiers during WWI and how it was perceived:
War Brings New Lingo
British Soldiers Enjoy Slang as Hospital Pastime.—Talk In Strange Metaphor—Visit to Operating Room Known as “Going to the Pictures”—Recruits From All Parts of World Add to New Language of Army Life in Europe.
London, July 21.— An entirely new crop of slang has come into force in the British army during the past year. They have taken the place of “blighty” and the rest of the picturesque synonyms that were uppermost a year or so ago. A hospital orderly writes about them as follows:
“There is a brand of cheap cigarettes, popular in the army, known by the name of ‘Singles to Woking.’ The allusion enwrapped in this mild witticism is typical of the oblique mischievousness which characterizes the best of Tommy’s slang. Tommy has a passion for what one might call the pseudo-grumble. He is a grouser who doesn’t mean his grousing to be taken seriously.
Jokes of “Danger Last.”
“Having served for two terms as an orderly in a war hospital, I may claim to speak with some assurance of that lovable, absurd, cheery malcontent — the British soldier. I have heard him crack jokes about a timber shortage, for instance. Can you guess why? Because he had found out that officially he was on what is known as the Danger List (and let me say that only a hero could crack jokes when in such a state as to be on the Danger List), and was voicing the charming theory that he might be ‘bilked of a coffin.’ That is our fearless and macabre Mr. Atkins all over. Another of his war hospital pleasantries is to announce that he is ‘going to the pictures.’ This is the regular phrase for the visit to the operating theater. And isn’t it rather fine?
“But I wish Tommy would rid himself of his habit of using rhyming slang. It is a curse, this vast list of synonyms which, I can only surmise, originated somewhere far back in the thieves’ latin of the tramp. Both the old army and the new are in the thraldom of the inane lingo. ‘Chevvy chase’ means ‘face,’ ‘mince pie’ means ‘eye,’ ‘false alarm’ means ‘arm,’ ‘almond rocks’ means ‘socks,’ ‘daisy root’ means ‘boot.’ I could (for my sins) continue the dismal catalogue down a column.
There’s considerably more at the Wordorigins thread; it’s a great look into the linguistic environment of 90 years ago.