抓辮子 [－辫－]

Jyutping zaau2 bin1 zi2
Pinyin zhuā biàn zi

Definitions (CC-CEDICT)
  1. to grab sb by the pigtail
  2. to seize on weak points
  3. to exploit the opponent's shortcomings
Definitions (Wiktionary)
  1. verb
    to capitalize on someone's mistakes or shortcomings