If I could force the public to watch one show, it would definitely be Penn & Teller: Bullshit!. In this show our favorite magicians/hucksters/Vegas residents tackle common beliefs, misconceptions, and other subjects and expose them for what they are: bullshit. Season one explored secondhand smoke, bottled water, feng shui, and alternative medicine, among other things. The second season (which was just released on DVD today) attacks such weighty topics as P.E.T.A., recycling, the war on drugs, and 12 step recovery programs.
The show is broadcast on Showtime, but I don't get that channel so I've had to wait for the DVDs. But they are well worth the price. Go pick these up and get educated.