"All About Lisa" is the twentieth episode and season finale of Season 19. It aired on May 18, 2008. This episode had the second lowest ratings in Simpsons history, with just 6.11 million viewers. Unlike most episodes, this one features narration by Sideshow Mel.
Lisa becomes Krusty the Clown's newest assistant and steals his spotlight. She wins the Entertainer of the Year award, but is warned that with her sudden fame comes a new attitude towards others and herself. Meanwhile, Homer and Bart bond over their newfound love of coin collecting.
At the 38th Annual Springfield Entertainer of the Year Awards, Lisa wins the entertainer of the year award (which won the 2007 Awardie Awards). Later Sideshow Mel flashes back to Krusty's 4000th Episode (guest starring Drew Carey as himself) to show how Lisa became an entertainer. Later Krusty shows a flashback clip of an earlier show with a group of singers called the Krustkateers (parodies of the Mousketeers) and is searching for new Krustkateers. At the tryouts Bart competes against Sherri and Terri, Milhouse Van Houten, Ralph Wiggum and Nelson Muntz but Bart unfairly loses to Nelson after Krusty slept with Nelson's Mother (though Krusty mistakenly calls Nelson "Wilber Mud"). Lisa then begins to tell Krusty that he was wrong to put Nelson on the show and suggests that he hires Bart as his unpaid intern; however, Lisa's plan backfires and Krusty hires her instead. Nelson is later fired and then Krusty puts on a show, but after Mr. Teeny can't make it to one of the shows, Lisa takes the opportunity to fill in for him and eventually becomes so successful she runs Krusty's show off the air and begins her own television show named "The Lisa Show", and soon Lisa is nominated for the annual entertainer of the year award.
Meanwhile, Bart is upset that he was not chosen for the job of working alongside Krusty so Homer decides to sell all of Bart's Krusty products to the Comic Book Guy so Bart can buy the new Radioactive Man comic issue of Radioactive Man vs. Muhammad Ali with the money but instead he is offered a copy of Radioactive Man Meets the Kansas City Royals so Bart changes his mind towards a copy of Radioactive Man vs The Restless Leg Syndrome but then he is offered a coin collecting book. Bart and Homer start coin collecting and after finding what they thought to be every coin in the book they find an extra slot for the "Kissing Lincolns Coin". Homer and Bart then find try finding it in a penny pile but instead after no luck go to an auction where the coin is being auctioned but they lose to Mr. Burns who wins the coin with a final bid of ten million dollars. Homer then manages to trick his boss into giving him four cents for a gumball, unknowingly handing over the Kissing Lincolns Coin in the process.
Later the flashback catches up to the present time where The Simpsons are at the 38th Annual Springfield Entertainer of the year awards where Lisa is handed the award, later in her personal changing room Sideshow Mel brings Lisa into the hall of fame where most of the stars pictured in the hall have lost their fame due to their busy lives. It is revealed there that Sideshow Mel is, in fact, one of them, and Lisa soon finds out the that the same fate could happen to Krusty too, so she indirectly gives all her fame to him and then goes home shortly after returning everything to normal.