I couldn't care less

US /aɪ ˈkʊdnt kɛr lɛs/
UK /aɪ ˈkʊdnt kɛr lɛs/
"I couldn't care less" picture
1.

全く気にしない, どうでもいい

used to express that one does not care at all about something

:
He was complaining about his new car, but I couldn't care less.
彼は新しい車について不平を言っていたが、私は全く気にしなかった
Whether they come or not, I couldn't care less.
彼らが来ようが来まいが、私は全く気にしない