(to close the gate and unleash the dogs to ward off burglars); to express that a place is closed and visitors are not welcome; a phrase used for telling coworkers that it's time to lock up soon so that they should hurry and finish what they are doing; a phrase used to warn those who come asking for trouble to watch out and be careful of their actions
Definitions (粵典–words.hk)
動詞、俚語
借喻閂門 to close the door, to pull down the shutters, to shut up shop