At a playground recently, a boy approached my nine year old and accused him of being stupid.

My son then asked "Why do you say that I'm stupid?"

The boy answered "Because I am cool."

Son: "Why do you say that you are cool"

boy: "Because I have awesome hair"

Son: "Why do you think you have awesome hair?"

At this point the boy became flustered, having exposed a vulnerability, and left my son alone. I'm sure one could do something similar.