Expressions used in Everyday Spoken English in Social and Professional contexts
The phrase 'come knocking on the door' means to contact someone usually with a request or an offer. This phrase can be used with positive and negative situations. If you say to someone 'don't come knocking on my door' you are telling them that you do not wish to be contacted by them, especially to ask for help. This phrase is much more likely to be used in a social context and is often said as a warning when someone thinks what you are about to do is a bad idea and that you will regret it later.