Use the verb disgrace to say that someone has brought shame upon himself. Your brother might disgrace himself at the family reunion by being rude to your Uncle Bob.
You probably notice that grace makes up a big part of disgrace. Combine this with the dis- prefix, meaning “the opposite of,” and you get a word that involves shame and dishonor. Think of disgrace as a kind of fall from grace — it’s what happens when you do something that causes you to lose favor or damages your reputation. You could disgrace yourself by losing your tennis match badly, or you could disgrace yourself by cheating on an exam.