打毒針 [－－针]

Jyutping daa2 duk6 zam1
Pinyin dǎ dú zhēn

Definitions (粵典–words.hk)
  1. 動詞
    喺​背​後​中​傷​人​，​捐​害​佢​嘅​聲​譽
    to discredit; to smear