it typically creates a one-word slang term out of a two-word phrase.
Well, not quite. The canonical process starts with a single word from which is derived a two word phrase (or two words linked with an AND) in which the second word rhymes with the one word being replaced. Then the second word of the two word phrase is dropped and the first word is used exclusively*. Example: Peaches and Cream for dream -- Oy 'ad the stryngest peaches last noight. This would result in a life vest being called a Mae. One problem here would be that I don't think the Brits would be likely to call the device in question a vest.
*This is not always the case; sometimes the whole two word phrase is used. This *would allow for the phrase Mae West to be used for vest, but see my objection above regarding use of the word vest to describe the life jacket. I also don't think that Cockney rhyming slang was a great source of military slang. But I could be wrong. I'm sure we have plenty of folks who can correct me.
