ANDY'S ANSWER:  What a bully loves most is a reaction. If they think they've gotten under your skin, it just encourages them so the key is to pretend whatever they've said to you hasn't bothered you a bit, or to shine a light on how nasty they are being, especially if they are with a group of people. Never get into a discussion about the actual things they are saying about you, because that just acknowledges it. What you want to address is the inappropriateness of what they are saying. That puts the spotlight back on them instead of you.