A man’s own good breeding is the best security against other people’s ill manners.

Your own manners are what protect you when someone else drops theirs. Rudeness works by getting a matching reaction, and the person who does not supply it stays in possession of the situation while the other loses it in public. That is not weakness, it is refusing to be conscripted.

The next time someone is short with you, answer at your normal temperature and finish the exchange properly. Say the courteous thing you would have said anyway. You will be surprised how often the other person adjusts, and how little the incident costs you afterwards.