S8E19: Grade School Confidential

In the episode titled "Grade School Confidential," Principal Skinner and Mrs. Krabappel's secret relationship is exposed after Bart catches them kissing during Martin's birthday party. Naturally, Bart uses this newfound information to his advantage, but eventually, the whole school finds out, causing a scandal. The couple is put under scrutiny by the Springfield Elementary School community and the PTA, who demand they end their relationship or face consequences. Instead of complying, Skinner and Krabappel decide to stand their ground and continue dating, leading to their dismissal from their jobs. In a twist of loyalty, Bart feels guilty for being the cause of their firing and helps the pair sneak back into the school. His plan involves getting everyone to realize how much they rely on Skinner and Krabappel. Eventually, Superintendent Chalmers reinstates them after realizing that maintaining discipline without them is impossible. The episode wraps up with Skinner and Krabappel resuming their roles at school, with their relationship now an open secret.