"I couldn't care less" is the literal way to state the sentiment, but it sounds weak and petulant compared to the idiom. There are multiple intonations that could potentially achieve the sarcastic effect, but the common one is just a flat dismissive delivery.
I agree with your observation of that common mechanism for mangling English, though. The mis-quote you mention is particularly embarrassing to behold.
I agree with your observation of that common mechanism for mangling English, though. The mis-quote you mention is particularly embarrassing to behold.