You're so clueless!
A: Did Tom just borrow money from you again?
B: Afraid so. He's really hit hard times.
A: You're so clueless! Didn't you notice his expensive new watch?
B: Oh, that! He said it was a birthday present.  

너 정말 눈치도 없다!
A: 톰이 너한테 돈을 또 빌려갔다며?
B: 그래서 걱정이야. 많이 힘든가봐.
A: 너 정말 눈치도 없다! 비싼 새 시계 차고 있는 것도 못 봤냐?
B: 오, 그래! 생일선물로 받은 거라고 그러던데.