most boring events

Merril Swain (1980) wrote:

If the phrase "could care less" is used by the speaker to mean least amount of caring and is understood by the hearer(based on both interlocuters' shared sociolinguistic competence) to mean such, then the phrase has been used correctly.

Language forms change. Get over it.

Hey, that's great. However, that still doesn't make that phrase an idiom. It makes it a phrase that is both spoken incorrectly and understood incorrectly, and therefore, interpreted correctly between the two parties.

In other words, the meaning is interpreted correctly by each party based on both interlocutors' shared sociolinguistic INcompetence.