頂ちょう門もんの一いっ針しん

expression, noun

painful reproach; a needle in one's scalp

Idiomatic expression for a sharp, stinging criticism that hits a weak point or exposes a fault. The literal image is of a needle piercing the top of the head.

• 彼かれの指し摘てきはまさに頂ちょう門もんの一いっ針しんだった。

  His remark was truly a painful reproach.

• 上じょう司しからの一ひと言ことが頂ちょう門もんの一いっ針しんとなり、自じ分ぶんの甘あまさに気きづいた。

  A single word from my boss became a needle in my scalp, making me realize my own naivety.