Zero shits given

The inability to give even one shit about someone or something, i.e. the situation in which one is unable to care. This term is also used to express dismay, disbelief, or sarcasm pertaining to someone or something, and can be a successful comeback comment in the event of a downward-spiraling conversation.

Simon: "Sophie, I asked you to complete that work before the meeting!"
Sophie: "Zero shits given, Simon."