Mystery Science Theater 3000 (affectionately shortened to MST3K)? It began years ago and basically the story is that this man is trapped on a spaceship with just a couple of robots for companions and is forced to watch "the worst movies ever made", which he and the robots mock and "riff"throughout. The premise is stupid, and we usually skip all the spaceship scenes, preferring instead to get to the good stuff-- the mockery of B-Movies, which is usually amusing and often laugh-out-loud hilarious. The two main stars are Kevin Murphy and Michael J. Nelson. Episodes included such films as: "I Was a Teenage Werewolf" and "The Brain that Wouldn't Die" and my kids' favorite, "Eegah! Most of them are pretty funny.
More recently, Murphy and Nelson (and another guy, Bill Corbett) have branched out, creating Rifftrax, wherein they make fun of older films and contemporary movies, from your favorite Star Wars six to "Jurassic Park" to "Captain America". With these modern films, instead of being able to just watch the movie with their dialogue overlaid like on MST3K, instead, you pay a nominal fee and download an MP3 track of their dialogue and watch the movie on a DVD which you have to provide. We have quite a few of these. Our favorites are "Thor" and one of the "Lord of the Rings" movies. My sons will roll their eyes that I couldn't remember which, but my brain just can't keep everything there. :)
It reminds me of how sometimes when I was a kid, my dad would turn down the sound on a movie and we would all join in making fun of it-- silly comments or fakey dialogue for the actors. It was always fun!
We have a separate speaker which we place on top of our surround sound receiver, with someone's ipod plugged into it, ready to play the MP3 Rifftrax for the film, then Murphy and Nelson tell you on the track how to sync up the film to their dialogue track. It's relatively simple to do, provided you have a way to hook up an ipod or your computer to a speaker to play the MP3.
Recently we watched "Thor" for the second time with Rifftrax, and it was even funnier than the first time. There were moments that I laughed until I cried. I really do recommend you go look for a movie you already own or can borrow from your library and spend the $4 or so for a Rifftrax. One good starter is "Jurassic Park", as it features the dependably funny Weird Al Yankovic as a guest riffer, and the DVD is widely available. Have fun!