What does the phrase struck a nerve mean?

"Struck a nerve" means to elicit a strong emotional response, usually negative, from someone. It implies that something said or done has touched upon a sensitive or painful subject for the person.

Here are some examples:

* "My comment about her weight really struck a nerve – she got really upset."

* "The article about the layoffs struck a nerve with many employees."

* "The politician's speech struck a nerve with voters who were feeling economically insecure."

Essentially, it means you've hit upon something that the person cares about deeply, causing them to react strongly.