.... about its wrong usage.
An article from Merriam-Webster humorously states,
"In an attempt to add another dubious assertion to our collection of rhetorical proclamations, we may state with absolute assurance that there are but two kinds of people in this world: those who feel very angry when someone omits a negative particle in “I couldn’t care less,” and those who don’t give such matters much thought. Is there a meaningful difference between these kinds of people, or these two phrases?"
I'm one of those who feel very angry! It drives me up the wall! (Idiom: used when something or someone makes you really annoyed).
The article goes on to say that either one is acceptable, which is also irritating (It's an American perspective!), but to be fair it does give some background - and is funny! You can read it here.
When taken literally, the two phrases have opposite meanings. "I couldn't care less" means that it's impossible for me to care any less about the subject at hand than I already do. If I say, "I couldn't care less about baseball," I mean that on a scale of one to 10—with 10 suggesting that I'm the most enthusiastic baseball fan in the world, and one meaning I don't give a toss about the sport—I'm a one. I don't care about baseball at all.
On the other hand, "I could care less" literally means "I care more than I might seem to." If you could care less, you're saying that you care some, which is the opposite of not caring at all.
Now, some people will argue that "could care less" is intended to be sarcastic and therefore shouldn't be taken literally. But it's hard to convey that in print, so it just looks like unpolished writing.
Stick with "I couldn't care less."
Sorry, if my criticism of Merriam-Webster and baseball conveys an anti-American sentiment. I love'em really - as long as they're not Trump supporters. So, I guess that I do like about 55%.
For a real rant about Americans' misuse of English, this video by British comedian, David Mitchell had me in stitches (Idiom; stomach cram due to laughing too much).
I'd like to say that I couldn't care less if I hear you using 'I could care less' about something you are not keen on.
But I could.
So - please!
Don't make me bang my head against the wall!
That's not me, by the way. I wouldn't look good with my head shaved.