a cheap shot
US /ə tʃiːp ʃɑt/
UK /ə tʃiːp ʃɑt/

1.
卑劣な一撃, 安っぽい攻撃
an unfair or unsporting remark or action, especially one made against a vulnerable person or at an opportune moment
:
•
His comment about her past mistakes was a cheap shot.
彼女の過去の過ちについての彼のコメントは卑劣な一撃だった。
•
The politician took a cheap shot at his opponent's family.
その政治家は対立候補の家族に卑劣な一撃を与えた。