to mention a subject that makes sb feel angry, upset, embarrassed, etc. :
You touched a raw nerve when you mentioned his first wife.
to mention a subject that makes sb feel angry, upset, embarrassed, etc. :
You touched a raw nerve when you mentioned his first wife.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005