Use It As A Teaching Opportunity
If you can take your child aside from a situation where another kid has been behaving rudely, talk to them about what happened. Ask them what happened, why it was wrong, and how they felt about it. Help them talk it through and really understand the poor choices that were made and why they were hurtful. If they can take the lesson to heart, they may not repeat their peer's mistake and even know how best to handle a situation like it in the future.