Kids' Discipline: Rude, Disrespectful Children
Children this age often begin to want more independence, but do not always express this desire appropriately. Your child is at an age when children are more subject to peer influences and may try out behaviors they hear or see other children do.
It is important to explain why his behavior is inappropriate and how it impacts you. Suggest an alternative behavior, such a way he can disagree without being disrespectful to you. Maintain your own temper and cool, because we cannot expect children to manage their own anger if we do not model management of our own feelings. If the rudeness continues, let him know the consequence for the behavior the next time it occurs. Then you must administer the consequence (which needs to be something that matters to your child) immediately and consistently the next time the behavior occurs.
Show your child, as you probably already do, kindness and respect and show it to others you interact with as well. Finally, explain why kindness and respect are important values to you and your spouse.