1:10 - 1:38 in the above video is one of the funniest scenes I've ever seen on TV. Jenna Elfman makes funny faces!
ETA: No, when I say Jenna Elfman makes funny faces, I mean Jenna Elfman makes HILARIOUS faces. I cannot help laughing every time I see the scene! Greg suggests that the stock market might be too complicated for Dharma, and she mocks him by doing a grotesque caricature of an airheaded bimbo. Also funny is Greg's helpless look of oh-crap-I-just-put-my-foot-in-my-mouth-a
The rest of the episode is good, too. As I recall, it's about Dharma trying to save a failing company that sells women's fashions for men, called edrag.com, and Greg's dad Edward coming out of retirement to help.