Someone created a website called Could Care to show the world that the common phrase "I could care less" is grammatically incorrect. I am guilty of using this phrase on the regular, despite knowing it doesn't make sense.
The intended meaning behind this phrase is that someone doesn't care at all, but if you think about it literally, "could care less" suggests they do care to some degree, since they could care less than they currently do.
The correct phrase to convey complete indifference is "couldn't care less." This means there is no possible way for them to care any less than they already do. On Could Care, you can slide a marker on a scale to show how much you care. If you slide the marker anywhere further than 0% of caring on the care-meter, it shows that actually, yes, you COULD care less, because you care at least a bit.
Personally, I get slightly annoyed when people correct my grammar during casual, everyday speech, but I think this website is a funny and great way to explain the silliness of this popular phrase.
See also: Apostrophe Protection Society wants to make sure we're using apostrophe's correctly
