I've seen several Mutt & Jeff cartoons, as I am apparently insane and love early animation. However, "On Strike" is brilliant and far better than the other examples of this series--and it actually ages pretty well despite its rather primitive animation.
Mutt & Jeff climb out of a reel of film when the movie begins. They walk down into the theater and catch a newsreel that shows Bud Fisher (the creator of the comic strip) going about town in style--in a limo and dressed in fancy duds. Well, the pair are angry--why does Fisher get to live like this and they get squat?! So, the pair go on strike and decide to make their own films! This is such a surreal film. Imagine cartoon characters coming out of the celluloid and begin jealous of their own creator?! It's all pretty crazy and shades of later films like "You Ought to Be in Pictures" (where Porky Pig enters the real world in 1940) and "Who Framed Roger Rabbit?". It also is a variation on the KoKo films by the Fleischers--where this clown would sometimes come out of an inkwell and walk about in the real world. My only complaint about this Mutt & Jeff cartoon is that sometimes the characters didn't really look like they were in the real world, as the animation style was a bit crude--but for 1920, you can't be too picky. Wildly exciting to watch even today and very creative.