.... But seriously, don't go attacking people that are being rude either.
I heard someone say once that "hate fought with hate just makes more hate" it sounds cheesy and all, but the reason a lot of people have the same opinion is because it happens all the time. A lot of unnecessary fights are started if you choose to react emotionally to people who are being disrespectful.
If you ever get the chance to study the history of war, it's likely you'll know exactly what I am talking about.
In all honesty, you're better off not saying anything to or about the rude people, and just encourage someone that is having a rough time with them.