Maybe I'll get flamed since this is the road bike forum, but my new fav one is the citibank one where the guy hasn't gotten his Trek mountain bike yet and is out there on the trail with his other 2 friends who have bikes, cept he's just hopping around with his hands in front of him like he has a bike but he doesn't then he trips and falls on his face going down a hill.
http://www.boardsmag.com/screeningro...mercials/1389/