Did you know that in 1990, Coors tried to extend their brand beyond beer and into sparkling water? You can watch the 45 second TV spot on You Tube HERE.
And the year before that, Pepsi tried to market a version with 27% more caffeine as a breakfast beverage, an alternative to coffee in the morning, called Pepsi A.M.? You can read a short New York Times article about Pepsi A.M. HERE from September 1989, which I thought was noteworthy because it states that Coca-Cola had already been trying to market Coke as a morning drink for several years as well. Pepsi A.M. failed to catch on (even if it was a less notorious flop than Crystal Pepsi). On hindsight, analysts pointed out that people who wanted to drink Pepsi for breakfast probably didn't think they needed a new, breakfast-specific version.
You can view a slideshow HERE of 25 other failed product extensions, including Colgate's attempt to move from toothpaste to frozen food ("Colgate Kitchen Entrees"), Smith & Wesson mountain bikes, and Ben Gay aspirin.