After the party, Bart, who fed his oysters to the Prince family cat, sees Principal Seymour Skinner and Edna Krabappel kissing in Martin's pink playhouse.
After failing to provide Bart with a convincing cover story, Edna and Skinner, fearing that they will be fired if anyone discovers their romance, swear him to secrecy in exchange for putting Milhouse's name on his permanent record.
Bart is humiliated in front of his classmates after Skinner forces him to say "I love you, Edna Krabappel" aloud as if the message were his own, with Martin making further jibes.
Fed up, Bart gathers the entire school in front of a janitor's closet and opens the door to reveal that Skinner and Edna are making out.
After hearing his son Ralph's risqué version involving the two "making babies", Chief Wiggum reports it to Chalmers, who gives Skinner an ultimatum: either he ends his relationship with Edna or they both will be fired.
Skinner decides that love trumps his professional goals, so Chalmers fires them and demands they leave the building by day's end.
With Bart's help, Skinner and Edna barricade themselves inside the school, contact the media and make their demands: they want their jobs back and the townspeople to stop interfering with their relationship.
When a disappointed Bart leaves, they observe grade-school children will believe anything they are told before entering the janitor's closet for another sexual tryst (also indicating Skinner was exactly the sort of person to lie about being a virgin).
[7] The authors of the book I Can't Believe It's a Bigger and Better Updated Unofficial Simpsons Guide, Warren Martyn and Adrian Wood, called it "A delightful episode that finally brings to fruition one of the series' longest running gags: Edna and Seymour's mutual attraction.