In this beauty shop episode, you'll see the classic "three gals under dryers with their hair in rollers" and Peggy gets even by chopping a woman's hair off. Marcy also gets her revenge for a bad hairdo too.
http://www.youtube.com/watch?v=wXDBz14IQPQ
http://www.youtube.com/watch?v=qP6havMA3H8
http://www.youtube.com/watch?v=ShupePlegr8