Head Shrinker Much?

S3, E23: A villain who wants to be the most evolved, advanced person on the face of the planet invents a crazy device which physically shrinks peoples' brains, causing them to regress to a more primitive state. Essentially, he's turning everyone into cave men. As society becomes more primitive, the world (including Beverly Hills), begins to turn into a lawless Mad Max-type society. In a b-story, Sam takes 'charm' lessons to impress an extremely cultured boy at school. Unfortunately, as she becomes more sophisticated, the boy she's trying to impress is turning into a brute of a caveman.