Most of the time people are rude it is because they themselves have problems. So, take the high road. Be nice in the face of even the most boorish of people. You will like yourself more when all is said and done then if you bend your own standards of decent behavior and act as rude as others do.
“If you want to slide through life, try being nice.” That is a quote from my father. He is also quoted in Murphy’s Law book, twice actually. But that is another story. My dad is right. Being nice confers benefits to you here and now and it is sooooo easy to do. Yes, other people around you are not always nice and polite and you will have to deal with rude people in your life. But that is no reason for you to act as a buffoon.