A phrase meaning "The degree to which
I care about this could not possibly go lower." Most people naturally interpret it to mean "I care about this as little as any human could; my degree of care is 0".
But it can also be interpreted to mean "I care about this to a certain extent (which may be a little or a whole lot) and there is
no way in hell my caring is ever going to drop."
Arguments about this can get pretty heated, with Team
Couldn't Care Less tending to care more.
"Guess what happened on
Dancing with the Stars last night?"
"Please don't bother me with that, I really couldn't care less about it."
"Mr. Politician, do you care about America?"
"I'm glad you asked that. I care about America more than anything in the world, and
I couldn't care less,
not in a million years. You'll have to pry my care from my cold dead hands."