[Yardstick]

The key is that “could care less” is sarcastic, so it means “couldn’t care less”. And it sounds so much better when spoken because it’s shorter and sharper with those two hard “c” sounds right next to each other. “Couldn’t care less” is more literal but nowhere near as stylish.

[goat granny]

not as stylish, but more accurate. Many use it not as sarcasm because they are not making a sarcastic remark, but too lazy to say the loooong word * couldn't * or don't know the easier way to say I don't care...imho (added imho so as not to get you so mad at me you could care less>):O)

[karnage]

In Chicago, we used to say, “I could care,” meaning, “I don’t care.”