狼狽為奸 [－狈为－]

Jyutping long4 bui3 wai4 gaan1
Pinyin láng bèi wéi jiān

Definitions (CC-CEDICT)
  1. villains collude together (idiom); to work hand in glove with sb (to nefarious ends)
Definitions (粵典–words.hk)
  1. 動詞
    壞人​合流​，​一齊​做​壞​事
    to be in cahoots; to collude
Definitions (Wiktionary)
  1. phrase, figuratively, idiomatic
    to act in collusion with each other; to work hand in glove with somebody (to nefarious ends)