If you haven't seen this movie... you NEED to. Especially if you like Trey Parker and Matt Stone. If you live or are from Colorado you will love it even more. Don't torrent it because you have to watch the commentary (drinking game included).
They filmed ALL OVER Colorado during Spring Break when they both went to CU. Places filmed include Keystone, Breck, Loveland Ski Area, Boulder, Gunni, Nederland, etc.