touch a nerve
触动神经，引起敏感或情绪化反应
口语·形容触及敏感点
英文释义
to mention a sensitive or controversial topic that elicits a strong emotional reaction
例句
When I mentioned his ex-girlfriend, I really touched a nerve—he got upset.
典故来源
源自医学上触碰神经引发疼痛的比喻，引申为提及敏感话题引起强烈情绪。