It varies depending on who is being rude to you, how well you know them, and under what circumstances. If for instance your boss is being rude, you work in customer service and a customer is being rude, or you are a child and your parents are being rude..etc It's probably not wise to be rude in return. In most instances you can say: I think it would be best if we focused on (blank) in order to accomplish whatever. In sales positions one is taught to first of all acknowledge what the customer wants or "empathize" with the customer by saying something along the lines of "I'm sorry you had to...etc or I understand. Let me see what we can do to ...etc
If it is a situation where you are driving and someone honks their horn or gives you the finger then it's probably best to ignore them. The same would hold true for trying to talk to someone that ignores you or hangs up on you.
The important thing to remember is you can only control (you). People (change) when (they) want to change. Your only power is in how you (react) as well as who you (choose) to spend your time with. Life is short! You always have the right to choose NOT to be around people that are rude or unkind to you.