"The Good, the Sad and the Drugly" is the seventeenth episode of Season 20.
When Milhouse gets suspended for a prank that he pulled, Bart promises to visit Milhouse every day. However, he meets a girl named Jenny, and starts a relationship with her. Meanwhile, Lisa does a report on Springfield's future, and becomes crestfallen, so Marge gets Lisa to take an antidepressant called ignorital.
When Bart and Milhouse pull a prank at Springfield Elementary, they unscrew every object in the building and watch as the entire school almost falls apart. Milhouse takes the fall and gets suspended from school. Homer forces Bart to sign in under Homer’s name and visit Grampa at the retirement home, and Bart soon becomes smitten with a delightful 11-year-old volunteer named Jenny. Hoping to impress Jenny, Bart offers to volunteer at the home. He invites her to his house for dinner, but as their relationship progresses, Milhouse emerges from his suspension and is less than thrilled about Bart turning his back on him for Jenny. Milhouse blackmails Bart until he cracks under the pressure. He tells Jenny his real persona, and begs her to stay, because she made Bart behave good for once. Jenny can't think of what to do, and breaks up with Bart. Homer then tells heartbroken Bart that girls come and go, but he would always have his family. This, however, makes matters worse for Bart.
Meanwhile, Lisa does a report on what Springfield will look like in 50 years and becomes very depressed at the dreary outlook. In class, she makes a dark speech on what will happen, horrifying her classmates and even causing one to jump out of the window screaming in terror. A concerned Marge takes Lisa to a counselor who diagnoses Lisa with Environment-Related Despair and puts her on an antidepressant medication to cure her eco-blues. The drugs make her see smiley faces and Lisa nearly kiss a fan (since she saw it as a smiley face), and Marge takes her off the pills. At the Kwik-E-Mart, Lisa tells Bart that he can't hide his problems, and must face them head on. Bart agrees, and buys flowers to as an apology. However, he apologizes to Milhouse, and Jenny is never seen again, because Milhouse has always been Bart's best friend. As a makeup prank, they ice the floors in Springfield Elementary, creating a massive ice rink.