You make them pay the consequences for their rudeness. Whether that's a time out or taking away a favorite toy or a favorite tv program or a favorite video game. Something that they value. Be firm and be consistent. When they know for certain that a price has to be paid for their actions, their actions in all likelihood will change.

Learning Behavior Management Skills can help you and your Child Every parent possesses the basic elements required to teach their child the essential behavior management skill and behavior tools. As a parent you practice these skills every time you step in to correct your child's negative behavior or praise their accomplishments. It is important that you show your children that by gaining control over yourself and your decisions, you will also gain better authority over those around you. When you are calm, but show firm authority over them it shows that you can stay collected while demanding action. This is a behavior management skill. Parent training has been proven to be a valuable tool in improving the abilities of children with many different types of behavior problems, and can even be helpful for those who have typical children. There is a recognized program, funded by the US Department of Education, which provides any tired parent training through parenting centers found nationwide. You can learn more about the program at http://www.taalliance.org/. Even though many of the behavior management skills taught in this parent training program are generally thought of as common sense parenting techniques, most parents would benefit from additional help and support in specific parenting skills, and how to use them consistently. At times it can be difficult for parents to learn the most important behavior management skills on their own. http://www.parentingteens.com/index/Teen+Behavior/Child+Behavior

One thing I have found is to isolate the child whenever he is rude. It can be for only a few minutes, as long as it takes for the child to agree to change his behavior. Sometimes it only takes a short talk, just say to him, "What you have said (done) is very rude. I do not allow that". If you make sure they are listening, and they will agree then and there not to do it again, that is enough. Be persistent, and repeat as necessary.

Assuming they aren't really little I would sit them down and tell them that from now on they have to earn privilages like computer time, new toys/clothes, outings with friends by obeying the house rules. Write down a few age appropriate rules and enforce them. Give examples of both appropriate and inappropriate behavior. Make sure you praise the kids when they handle their negative feelings properly. When they are disrespectful talk to them after they have calmed down about how they may have better handled the situation.