Bullying behavior is a precursor to predatory behavior. Bullying exists in a number of forms, but it is passive-aggressive because bully tactic is a reconnaissance, not an attack itself. The goal of bully tactic is to evaluate the relative strength of the victim and assess whether [or not] that victim is a target for predatory behavior. The predatory behavior is the attack that antecedes the bully tactic.
In children, bully behavior is a natural response because they do not understand social context, so the violation may be innocent. In school, the same playground behavior that earns a trip to the principle's office would be lauded on a football field. Children can be confused by this double-standard because they do not yet understand the appropriate context in which to act. Of course, it can also be selfishly predatory (I like that doll, I want your snack, etc.).
As adults, bully behavior takes advantage of social context. Bullies know that aggressive behavior is not desirable. As many of these posts confirm, we are in fact committed to not being counter-aggressive in the face of aggression, but concilliatory. In this social context, the bully takes advantage of our committment.
I believe a key to defusing bully behavior is to return a non-predatory response to bully tactic, thus deterring predatory action. That response can range from verbal to physical, but it must contain the message, "I am not a victim." I believe the more skillfull we become at addressing conflict, the better we can focus our response thus soliciting maximum effect for minimum response.
A keen Chuck Norris stare with the quip, "I can kill you with this tea cup," will not suffice...unless you can back up that statement. (Mr. Norris can, by the way).
As a side comment, it takes a fair amount of courage to adequately respond to bully tactics because we naturally are adverse to conflict; there is nothing wrong with committment to peace. Some of the smallest mouths (i.e. non-talkers) out there on this topic have the largest voices when it comes to showing this courage.