A cornered rat will bite a cat — a proverb meaning that someone desperate or backed into a corner may fight back unexpectedly.
小さな会社でも倒産寸前になれば窮鼠猫を噛むように強硬な手を打つことがある。
Even a small company, when on the verge of bankruptcy, may take drastic measures like a cornered rat biting a cat.
彼は普段は温厚だが、窮鼠猫を噛む性格で、追い詰められると反撃する。
He is usually mild-mannered, but like a cornered rat he'll bite — when pressured he fights back.