I have had similar problems before, but the guy has not knocked on my door. It usually happens when we are out front on the porch or something. He comes up the steps to our building and tries to shake your hand. He says the same thing each time, that it is his “birthday” and he has been cleaning up garbage on the street all day. Then he asks for money obviously. I have seen him do this to almost every neighbor that is outside at the time.