彈冠相慶 [弹－－庆]

Jyutping daan6 gun3 soeng1 hing3
Pinyin tán guān xiāng qìng

Definitions (CC-CEDICT)
  1. lit. to flick dust off sb's cap (idiom); to celebrate an official appointment
  2. to congratulate and celebrate (promotion, graduation etc)
Definitions (Wiktionary)
  1. phrase, derogatory, idiomatic
    to congratulate each other