Sometimes, when manager asks me what's the estimate, and I think it's just too much to reply... I ask back - "Why are you asking this though?". It's weird, but

Sometimes, when manager asks me what's the estimate, and I think it's just too much to reply... I ask back - "Why are you asking this though?". It's weird, but usually I get in response something, that make me really understand well what to reply to them.