The first Cow and Chicken short had rougher animation than the series that followed and featured much darker themes. In the first cartoon, Chicken goes to hell for smoking cigarettes and is tortured by the devil while he's there. After this harsh episode, the content of the series was significantly toned down, the animation was brightened up, and the devil's name was changed to "The Red Guy". See more
[Chicken thinks he should miss school, because he has to take care of his new egg
I don't want you skipping school because of your "Being in the family way", and all.