You need some staircase wit, to let people know when they're being mindlessly (or mindfully) hurtful. Watch this:

http://www.youtube.com/watch?v=PyQ_IKkAM9I

If you haven't seen Joy Nash (her fat rants are on You Tube, just search for her name), you should...not only is she hilarious, but she makes a lot of sense. Her rant on staircase wit is about having the self confidence to realize that you don't have to take harsh comments (nor do you have to be a total b-tch in order to stand up for yourself).

Hilarious video!!!!!!!
She has several others and a blog