The tv comedy Mind your language ran from 1977 to 1979. I use it occasionally in class to illustrate vocabulary, grammar and communication. One episode (“Many happy returns”) is largely about money. It starts with Sid the college caretaker asking Gladys the tea lady for a free cup of tea, because he’s (something). She replies “You’re always skint, Sid!”. The subtitles (whether auto-generated or created by a human – some episodes are better than others) have “I’m a bit glacier mint”, but audibly that’s not what he says. I had always guessed that it is rhyming slang, as several other episodes show him using that, and even attempting to teach it to the students (one of whom refers to it as “cockeyed slanging rhyme”).
Fast-forward to a few days ago, when I was browsing through a book which I’ll donate or throw away soon. It has a section on Cockney rhyming slang, and one of the items is boracic lint. That is indeed what Sid says, but what is it? Wikipedia explains, quoting its entire article:
Boracic lint was a type of medical dressing made from surgical lint that was soaked in a hot, saturated solution of boracic acid and glycerine and then left to dry.
It has been in use since at least the 19th century, but is now less commonly used. When in use, boracic lint proved to be very valuable in the treatment of leg ulcers.
The term “boracic”, pronounced “brassic”, is also used as Cockney rhyming slang for having no money – “boracic lint” → “skint”.
So was is the origin of skint? Probably from skinned. This is a word in my passive vocabulary – I understand it when I hear or read it, but never use it myself (informally, I would say broke). I can’t remember it being used in any Australian context, so my familiarity must be from British English sources, but I can’t pin it down to any one in particular.
But glacier mints are a thing, too. Are they ever used as rhyming slang? A well-known search engine pointed me to this site, which records alongside boracic lint: peppermint, polo mint, murray mint, Bernie Flint, Harry Flint, Jackie Flint and Larry Flint, but not glacier mint. Which doesn’t mean that glacier mint isn’t used as rhyming slang, just that it’s not recorded on this site. If the subtitles were created a human, that person might use it, or otherwise have reached (mentally) for the presumably more familiar glacier mints instead of the less familiar boracic lint.
(I note that that rhyming slang is not limited to Cockneys (in the east end of London); Wikipedia says: “In the United States, especially the criminal underworld of the West Coast between 1880 and 1920, rhyming slang has sometimes been known as Australian slang.”)