I've found this to be a common Americanism, but it's still incorrect, I believe. When I moved to the US in my teens, I was surprised at the sheer disregard of English grammar rules in common vernacular here, to the point that some folks (though not my English teachers) think their incorrect use is correct. :) The most marked case I saw was in a Dodo video where the person correctly said "lying", but The Dodo's captions "corrected" it to "laying".

But I digress.

The fun thing about grammar is if enough people do it and think it's correct, it's correct. Languages change.

Linguistics should seek to be descriptive rather than prescriptive. The field should, primarily, seek to describe language as used. Prescriptions can be useful and should be made if they improve a language's ability to provide clarity (please mind the theirs and toos, and sometimes an Oxford comma would clarify your sentence) but they should be held to be mere suggestions and not authoritative mandates.

The idea that there is only one correct way to use a language and that it is determined in academic circles and should be enforced on the masses is inherently based in illegitimate authority and social exclusion and is not a social force for good.

Languages evolve over time. Someone's rules from 200 years ago need not apply, just as they likely didn't apply 200 years prior to that.

I could care less about your explanation!

> When I moved to the US in my teens, I was surprised at the sheer disregard of English grammar rules in common vernacular here, to the point that some folks (though not my English teachers) think their incorrect use is correct.

You noted a common feature of incorrect Americanisms, which is that many of its speakers proudly and ignorantly proclaim their usage is correct. Disregarding descriptive linguistics, all it takes is one second of logic to realize why an incorrect saying doesn't make sense at all, but even that is asking for too much without getting into an argument sometimes.

bait?

It's *couldn't care less my dude

Maybe reconcile in your mind the first line with the follow-up explanation to see whether it's bait or not and if it should be taken seriously.

> I could care less about your explanation!

Maybe you should care less about it then.