For example, many people say, "I could care less."
Really? You could?
So there's something else out there that you have less concern about than what we're talking about now, right? Or, you care a little more now than you think you should?
"I could care less what people think."
So you do care about what they think, and there is a point lower in your caring levels, but you just don't want to go there right now.
The saying is, "I couldn't care less."
That is, you are at the most apathetic you can possibly be regarding whatever issue it is that you are talking about... Basically, you want to say you just don't give a flying fuck. "I could not care [any] less [than I do now]."
Oh, and people.... A LOT is still two words... we still haven't combined it into one. "A" is an article, related to "an" and "the". "Lot" is a noun. I mean, you don't spell 'parkinglot' as one word, or write out 'agiant', or 'alittle', do you? Well, maybe you do. Time to return to grade school if that's the case.