I "could" care less means you actually care, even if just a little. Why do people now say "hating on" rather than just "hating"? On? On what? A donkey? Why do some people begin sentences with the word "So"? The word is a conjunction, like "and", "but" and "because". Don't they teach these things in primary school anymore? If not, why not?
A great video that explains it well :)