폐부를 찌르는 말 · 폐부를 찔렀다 (르 irregular)
to cut to the quick, to strike home, to pierce the heart
Example
선생님의 한마디가 제 폐부를 찔렀어요.
My teacher's single remark cut me to the quick.
Word parts
폐 lungs+부 innards
Literally 'to pierce the lungs and innards' — words that reach your deepest feelings.