With "bullying" being a hot topic, here is some information to consider when talking to your child(ren).
Calling someone a bully is not helpful, it is hurtful. Instead, try pulling the behavior away from the child. Talk about how bullying behaviors are hurtful not label a kid as being bad. Kids are kids and all kids(and adults) make mistakes. Even if a kid exhibits bullying behaviors, (s)he can learn to change and grow. Haven't we all?
We all have negative altercations; what's the best way to deal with them?