idiom
give someone a dose of their own medicine
誰かを自分が他の人にしたのと同じように悪く扱うこと
Meaning
to treat someone the same bad way they treated others
Example
He was rude to everyone, so I **gave him a dose of his own medicine**.
彼はみんなに失礼だったので、私は**彼にも自分のやり方で対応した**。