`To drink tea` as a slang in Chinese means to be asked to talk with authority, especially the police, etc., which is generally not regarded as a good thing.<p>Similarly, `to check the water meter` and `to receive a post package` mean the police to come to your door, as the police are thought to be disguised as staff from tap water company&#x2F;package delivery company, in both cases, you are about to open the door.