Well, I hate hearing Sir and Ma'am or worse, Madam. And I detest people calling me by my name (even Mr. BP) if we don't know each other / haven't been introduced. I would never say 'guys' on a PA, but to a group of students or young people, sure. However, in other languages, I use the equivalent of Sir and Madam all the time, because that's the cultural norm for those languages. I would not sweat the small stuff, but if it really bothers you, tell them to call you 'Your Royal Highness' or what ever it is you want... just don't expect the small talk to continue as they will be afraid of re-offending you.