Bart is taunted by school bullies Nelson, Jimbo, Dolph and Kearney because he does not have a real 10-speed bike as they do. In order to get Homer to buy him one, Bart places his current bike so that it is run over and destroyed by Dr. Hibbert. Homer buys the 10-speed for Bart, but refuses to pay the small assembly fee and builds it himself. Bart is happy since it looks great and works perfectly at first, but it falls apart when he moons the bullies. Homer, wanting Bart to be proud of him, tries to build a battle robot for the show Robot Rumble. He fails to construct one, and instead assumes the identity of one, which Bart names "Chief Knock-a Homer". Unaware of Homer's ruse, Bart enters the robot in the Rumble.
Meanwhile, Hibbert's car runs over and kills the Simpsons' cat Snowball II,1 shortly after crushing Bart's bike. A devastated Lisa recites a poem tearfully at the funeral, where Snowball II is buried next to Snowball I.2 Lisa adopts a ginger cat, which she names Snowball III, but he drowns in the fish tank.3 The next cat, Coltrane (Snowball IV), jumps out of a window after hearing Lisa play her saxophone.4 The owner of the cat sanctuary refuses to give Lisa any more cats, but the Crazy Cat Lady wanders past and throws a cat at Lisa that strongly resembles Snowball II.5 Although Lisa tries to shoo the cat off, worried that she will meet the same fate as the others, the cat survives a near miss on the street when Gil Gunderson swerves to avoid hitting her while driving and crashes into a tree. Lisa decides to keep the cat, officially naming her Snowball V; however, the family will call her Snowball II in order to save money on a feeding dish. Principal Skinner comments disparagingly on the choice, but relents when Lisa points out that the same had previously been done for him.
Homer defeats numerous opponents and makes it to the finals, despite being injured from the battles with the other robots. In the final match against Professor Frink's undefeated Killhammad Aieee, a super-robot of both impressive design and skill, Bart finds Homer in “Chief Knock-a Homer” after the grueling first round. Caught, Homer apologizes to Bart, but Bart is impressed because of all the pain Homer went through to win his son's admiration. However, by then the second round has begun, and Killhammad Aieee grabs “Chief Knock-a Homer”, with Homer still inside, to finish the fight, until it squeezes Homer out of the robot and immediately stops as soon as it sees him. Frink explains that the robot follows Isaac Asimov's Three Laws of Robotics and has been programmed to serve humans rather than harm them, with Killhammad Aieee setting out a chair for Homer and pouring him a martini. Homer wins the match (although one of the commentators points out that the tournament rules prohibit any human combatants) and Bart is proud of him.
The episode was watched by 16.30 million viewers, which was the 13th most-watched show that week.9
Colin Jacobson of DVD Movie Guide was critical of the episode, saying it "starts pretty well but droops before too long. The robot theme is too silly, and the cat sequences are too morbid. Some of the battle bots bits amuse, but they're not enough to overcome the episode's general flaws."10
On Four Finger Discount, Brendan Dando and Guy Davis liked the episode because it showed Homer being a good father and also because they were fans of Robot Wars.11
Delaney, Tim (December 2, 2009). Simpsonology: There's a Little Bit of Springfield in All of Us. Prometheus Books. p. 135. ISBN 9781615921348. 9781615921348 ↩
Halpern, Paul (2007). What's Science Ever Done For Us?: What the Simpsons Can Teach Us About Physics, Robots, Life, and the Universe. Wiley. ISBN 978-0-470-11460-5. 978-0-470-11460-5 ↩
"National Nielsen Viewership (Jan. 5-11)". The Los Angeles Times. January 14, 2004. Archived from the original on May 14, 2023. Retrieved June 10, 2023 – via Newspapers.com. https://www.newspapers.com/article/41428762/the-los-angeles-times/ ↩
Jacobson, Colin (December 13, 2012). "The Simpsons: The Complete Fifteenth Season (2003)". DVD Movie Guide. Archived from the original on August 6, 2017. Retrieved October 27, 2024. http://www.dvdmg.com/simpsonsseasonfifteen.shtml ↩
Davis, Guy; Dando, Brendan (April 15, 2022). "I (Annoyed Grunt) Bot (S15E09)". Four Finger Discount (Simpsons Podcast) (Podcast). Event occurs at 1:40. Archived from the original on July 23, 2024. Retrieved October 27, 2024. https://fourfingerdiscount.podbean.com/e/i-annoyed-grunt-bot-simpsons-podcast-review/ ↩