I could care less
This phrase is for brainless people who think they're being cool. They really mean 'I couldn't care less,' but they’re too dumb to know the difference. It’s like saying 'I’m kind of not interested' when you’re completely not interested.
'I could care less about this dumb movie,' said the kid who fell asleep halfway through it.
'I could care less about the homework,' said the kid who didn’t even do the homework.
'I could care less about the concert,' said the person who didn’t even show up.