The rules of interaction depending on context and demographics, to put it roughly.
Youth examples:
- You may swear in conversations with peers, but you should not in conversations with people higher in the hierarchy.
- When people ask "how are you?", they are not genuinely asking in most cases. It is just a greeting. But there are exceptions like your grandmother and a teacher you have not seen in years, but are close to.
Adult examples:
- You can tell a rich person about your great vacation, but not a poor person. If you have a high paying job, you are expected to be happy when talking to a person who earns less than you do.
- Random men (I am also a man) will find it completely appropriate to start a conversation with you discussing the body parts of a nearby woman. It has happened enough times that otherwise successful people view it as an appropriate way to start a conversation on a train. Pretty sure they do not do that with non-peers/women as it is pretty creepy.
- For a more comic take: https://www.youtube.com/watch?v=Tms0yk9kqVM. Basically the war should not be mentioned by a Brit to a German, but you can mention the war to another Brit.
Changing how you present yourself to match the social environment you're in. Formal vs informal speech, mannerisms, what is appropriate behavior in context, all of that sort of thing.
