"Sweet Seymour Skinner's Baadasssss Song" is the nineteenth episode of Season 5. It first aired on April 28, 1994. The episode was written by Bill Oakley and Josh Weinstein and directed by Bob Anderson. This is the 100th episode in production order.
It is show-and-tell day at Springfield Elementary School, and seeing how most kids have geodes or other random items, Bart brings his dog, Santa's Little Helper, to school. Everyone is excited to see Bart's dog, but Santa's Little Helper shortly makes his way through the school vents, when he is put away in a closet and is spotted by Ralph Wiggum. Groundskeeper Willie is greased up and sent inside the vents and retrieves the dog (the dogs licks his foot tickling him causing the children who can hear him laughing to throw objects at the vent where he was) after informing Principal Skinner who is talking in the phone, but Superintendent Chalmers shows up, in detest after hearing about the dog. At first, Chalmers looks into Santa's Little Helper's eyes and forgives Skinner for what's happened. But after a falling Willie lands on the "bloated gasbag," that is the last straw. Chalmers fires Skinner on the spot, and Bart is guilty because of his dog.
Skinner rejoins the army, but manages to gain a friendly relationship with Bart, even going out to Luigi's to eat. During these events, Ned Flanders becomes the new principal, and is very lax with the rules. Due to this, the school breaks out in chaos and the kids vandalize, tag and even lock Martin Prince up in a cage. Bart feels bad for Skinner, and wants to try to get Flanders fired. Superintendent Chalmers shows up to do another inspection of the school, and Bart convinces him to fire Flanders because of the chaos the kids can make with impunity. Chalmers then hears Flanders ask the students to "thank the Lord" over the intercom, and because you're not allowed to promote a religion in public school, Flanders is fired and Skinner becomes principal again. Skinner and Bart know they can no longer be friends now that Skinner is principal again, so they say goodbye and walk away, feeling good.