The popular humor website Funny or Die has featured many exercise-related parodies and sketches over the years. As a matter of fact, I found a P90X parody there, too. Recently I discovered these are conveniently located here (topic name: Exercise), along with some related blog posts and images.
I’m not going to recommend anything specific. Some of these are “clean” comedy, some are a little inappropriate, and others… are probably best left up to your discretion. I found at least a couple that made me LOL, as the kids say, maybe in spite of my better judgement. In my opinion, it’s always good to poke a little fun at the fitness industry, advertising, and maybe even ourselves once in a while.