Locked doors
Reddit was used by a user to express her discomfort at meeting her neighbor. He asked her why she had locked her door when she was in. She asked him then how she knew. He replied that he had tried opening the door multiple times.
Throwing Soup
One user’s neighbor was known to throw soup from their window. The neighbors live on the 16 thfloor and if they threw the soup out of their window, it would cover all the windows below. These neighbors refused to open the door for the user when he came in to complain.