I don't care
1. I have no preference. A: "What do you want to have for dinner?" B: "I don't care—you can pick."
2. This does not bother or upset me. Often used passive-aggressively, as to hide one's actual feelings of upset. A: "I don't care what Scott does now that we're broken up." B: "Are you sure about that?" She can say whatever nasty thing she wants about me—I don't care.
I don't care.
It doesn't matter to me. Mary: Can I take these papers away? Tom: I don't care. Do what you want. Bill: Should this room be white or yellow? Sally: I don't care.