You don’t always need to stand up for yourself especially if there is nothing you can do about a petty situation. Pick your battles wisely. Often people who react negatively regret their behavior when they calm down. But if you counter with negative energy, they are more likely stick to their story and justify their jerkiness. If instead you surprise them by shifting your attention elsewhere, you remove energy from the fight. They might give in once their ego is no longer involved.
There will be times you need to stand up for yourself. If you feel your reputation as a strong or your soul needs you to speak your truth, please do so. And if reacting to a rude person is a waste of time, let it go.