On caring.

The phrase for which you are groping, oh interlocutor with illusions of pithy articulation, is

"I couldn't care less."

If you want to make your point, not undermine it, you'll need to remember that "n't" represents a not, which here indicates that you care so little about the matter at hand that it would be impossible for you to care less about it.

Tighten that up, savage.