Dictionary / Vocabulary / 闇夜に鉄砲
やみよにてっぽう
aimless attempt; shot in the dark
闇夜に鉄砲じゃあるまいし、そんな場当たり的なやり方でうまくいくとは思えないよ。
That's just a shot in the dark. How do you think you'll succeed by just acting on the spur of the moment like that?