The Simpsons - Season 12 - Eps 9: HOMЯ
While working as a human guinea pig (to pay off the family's lost savings after making a bad investment), Homer discovers the root cause of his subnormal intelligence: a crayon that was lodged in his brain ever since he was a boy. He decides to have it removed to increase his IQ, but discovers that being smart does not necessarily equal being happy.
About The Simpsons

Title: The Simpsons
First Air Date: 1989-12-17
Last Air Date: 2025-05-18
Status: Returning Series
Rating: 8/10 (from 10314 votes)
Language: EN
Seasons: 38
Total Episodes: 787
Network: FOX
Genres: Family, Animation, Comedy
Production Companies: Gracie Films, 20th Century Fox Television, 20th Television Animation, 20th Television
Synopsis
Set in Springfield, the average American town, the show focuses on the antics and everyday adventures of the Simpson family; Homer, Marge, Bart, Lisa and Maggie, as well as a virtual cast of thousands. Since the beginning, the series has been a pop culture icon, attracting hundreds of celebrities to guest star. The show has also made name for itself in its fearless satirical take on politics, media and American life in general.
Cast

Dan Castellaneta
Homer Simpson / Abe Simpson / Barney Gumble / Krusty (voice)

Julie Kavner
Marge Simpson / Patty Bouvier / Selma Bouvier (voice)

Nancy Cartwright
Bart Simpson / Nelson Muntz / Ralph Wiggum (voice)

Yeardley Smith
Lisa Simpson (voice)

Hank Azaria
Moe Szyslak / Chief Wiggum / Apu / Comic Book Guy / Carl (voice)

Harry Shearer
Ned Flanders / Mr. Burns / Smithers / Skinner / Lenny (voice)