When people say
"could care less" instead of
"couldn't care less". There's a difference: the meaning of the sentence!
You're trying to imply you dont care- hence
'couldnt care less'-you care so little, its not possible for you to care any less than that.
'Could care less' implies that you do care somewhat, so you're saying you could care less- which sounds like you care more than you should.
It might sound obvious. But apparently it's not
.