ding ni ge fei
It literally means 'block your lungs'. Basically used as 'god forbid', in cantonese.
Person A: Ni gum yut be che zong mo?
Person B: Ding ni ge fei!
Translation:
Person A: Did you get run over by a car today?
Person B: God forbid.
Person B: Ding ni ge fei!
Translation:
Person A: Did you get run over by a car today?
Person B: God forbid.