- Eugene H. Krabs
- Sheldon J. Plankton
- Debbie Rechid
- Sandy Cheeks
- Patrick Star
- Karen Plankton
- Human crowd
- Abigail Marge
- Purple Fish
- Fred (normal; blue)
- Harold "Bill" Reginald
- Frankie Billy
- Squidward Tentacles
- SpongeBob SquarePants
- Nat Peterson
- Mrs. Puff
- Frank the Red-Shirt-Wearing Fish
- Medley Fishbowl
- Sheldon the Fish
- Frank the Lifeguard
- Nancy Suzy Fish
- Nathiel Waters
- Vera Fishbowl
- Norma Rechid
- Jennifer Millie
- French Narrator
The episode begins on another beautiful day at the Krusty Krab. Mr. Krabs once again foils another one of Plankton's attempts to steal the Krabby Patty Secret Formula and kicks him out. When Sandy notices Plankton and learns that he was trying to steal the formula, Plankton comments on how disappointing it is that Mr. Krabs constantly manages to thwart his efforts, despite the latter's overall lack of general intelligence. Sandy claims that Mr. Krabs would have to be as dumb as Patrick for Plankton to actually succeed in stealing the formula. This gives Plankton an idea.
Plankton breaks into Patrick's rock and takes a sample of his saliva. Plankton then makes the sauce in his kitchen, which smells horrible. Plankton explains to Karen that when he adds Patrick's saliva in the sauce, it will become Salsa Imbecilicus (aka, "Idiot Sauce"). He plans on giving the sauce to Mr. Krabs so he will become as dumb as Patrick and get the secret formula. Karen tries helping Plankton make the sauce, since he tends to mess things up, but Plankton refuses her help. But after Plankton adds Patrick's saliva to the sauce, it boils over and some of it splatters on to him, causing to become as dumb as Patrick. The steam from the sauce gets flown through the chimney and absorbs a nearby cloud. The cloud then rains the sauce over Bikini Bottom, which causes the whole town to become as dumb as Patrick.
The next day, Sandy notices that everyone, including her friends, is acting stupid. She learns about the accident from Karen---Karen deduces that Sandy wasn't affected because she must have been in her treedome at the time while Sandy figures that Karen wasn't affected due to the fact that she's a computer. They try snapping Plankton out of his idiocy by doing many things like shining a light on him, feeding him with nuts, and even simply yelling at him. But their efforts were no avail. However, after Karen points out that being smart takes work, Sandy gets an idea—she and Karen start Bikini Bottom University to try and educate the entire town back into their normal selves. By the end of the semester, Karen and Sandy have managed to educate the entire town except for Plankton, who continued to act dumb and became a school bully (particularly to Mr. Krabs).
On the day of graduation, Mr. Krabs perfects the Krabby Patty secret formula in Home Economics, but when Plankton gets a taste of it, he tries forcing Mr. Krabs into giving him the formula. However, SpongeBob shows up to give Mr. Krabs his diploma, as neither he nor Plankton had shown up for the ceremony. It also turns out that Mr. Krabs had taken accelerated classes and actually graduated months ago—it also turns out that he was never actually scared of Plankton, but was just acting it out for an acting class he was taking. Sandy gives Mr. Krabs his final grade for it (an A+) and Mr. Krabs launches Plankton outside through the window, where he smacks into Karen's computer screen. Karen takes Plankton home so he can start his "post-college years."
|( ‣ ) Associated production music|
|( • ) Original music|
|( ◦ ) SpongeBob music|
‣ Peg Leg Waltz - Michael Bolger, Nicolas Carr, Sage Guyton [Title card.]
‣ The Rake Hornpipe - Robert White [Krabs kicks Plankton out of the Krusty Krab.]
‣ Fooling Around - Barry Anthony [Sandy talks to Plankton.]
‣ Hot Steel and Slide Licks (c) - Jeremy Wakefield [Patrick rides a skateboard on the wrong side.]
‣ Vibe Q Sting - Nicolas Carr [Plankton gets an idea.]
‣ Tales from the Swamp (a) - Ron Goodwin [Plankton laughs diabolically.]
‣ Agitation [#29] - Phil Green [Plankton in Patrick's mouth.]
‣ The Fruitcake Vendor - Nicolas Carr, Barry Anthony [Plankton making sauce.]
‣ Dramatic Bridge 7 - Phil Green ["Idiot sauce!"]
‣ Hot Steel and Slide Licks (e) - Jeremy Wakefield ["I think I prefer the boiling underpants."]
‣ Break In - Harry Lubin [Plankton mutes Karen.]
‣ Dark and Scary - Harry Lubin [Cloud absorbs idiot gas.]
‣ Cloak and Dagger [#70] - Phil Green [Cloud rains idiot sauce on entire town.]
‣ Gator - Steve Belfer [Sandy sees citizens acting like idiots.]
‣ Hot Steel and Slide Licks (u) - Jeremy Wakefield [Patrick puts a balloon in his mouth.]
‣ Gator - Steve Belfer [Krabs throwing money around.]
‣ Vibe Sting - Nicolas Carr [Sandy sees a line at the Chum Bucket.]
‣ Hot Steel and Slide Licks (r) - Jeremy Wakefield [A fish sucks Sandy's helmet.]
‣ Clowning Around - Barry Anthony [Karen explains to Sandy what happened.]
‣ Cartoon Sting 9 - Barry Anthony [Sandy and Karen trying to snap Plankton out of it.]
‣ Harp Ding - Nicolas Carr [Sandy gets an idea.]
‣ Skyline - Anthony Mawer [Karen and Sandy create Bikini Bottom University.]
‣ Lipstick and Charm - Wilfred Burns [Montage of Sandy and Karen educating everyone.]
‣ Befuddled Gent - Phil Green [Plankton writing graffiti.]
‣ Seaweed - Steve Belfer [SpongeBob stuffed in locker.]
‣ Hot Steel and Slide Licks (c) - Jeremy Wakefield [Patrick as a janitor.]
‣ Legion of Honor [#22] - Harry Bluestone [Graduation day.]
‣ ? - Nicolas Carr [Squidward playing clarinet.]
‣ Sneeky - Gregor Narholz [Krabs making a Krabby Patty.]
‣ Unknown Track 45 - Nicolas Carr ["Yes! That's it!"]
‣ Tipsy Turvy - Phil Green ["Something smells good!"]
‣ Dramatic Bridge 4 - Phil Green ["With this recipe, I could own the most popular fast food restaurant in Bikini Bottom!"]
‣ Pomp and Circumstance #1 (a) - John Fox [Graduates throw their caps into the air.]
‣ Hawaiian Adventures SpongeBob Theme - Sage Guyton, Jeremy Wakefield [SpongeBob goes to give to Mr. Krabs his diploma.]
‣ Danger Sign - Harry Bluestone, Emil Cadkin [Krabs about to give Plankton the formula.]
‣ Harp Ding - Nicolas Carr [Krabs gets his diploma.]
‣ Peg Leg Waltz - Michael Bolger, Nicolas Carr, Sage Guyton [Krabs says he graduated months ago.]
‣ Hot Steel and Slide Licks (x) - Jeremy Wakefield [Krabs gets an A+ in acting.]
‣ The Rake Hornpipe - Robert White [Ending.]
- This episode is available on The Complete Ninth Season DVD.
- As of September 29, 2017, The Internet Movie Database (IMDB) gives this episode a rating of 8.5/10 based on 74 ratings by users. TV.com users give this episode a rating of 7.7/10 based on 14 votes.
- This episode was originally going to be called "Idiot Sauce," but the title was changed because it sounded too mean.
- Karen breaks the fourth wall by playing a laugh track after Plankton gets humiliated.
- Before the episode aired, a lot of people were confused by the word "Imbecilicus" in the episode's title, until they found it was a made-up word used by Plankton for the name of the sauce he created.
- Running Gags: Karen playing a laugh track after each humiliation and Patrick riding a skateboard upside down.
- This is the second time SpongeBob has a lump on his head. The first was in "What Ever Happened to SpongeBob?"
- This is the first appearance of the Bikini Bottom University.
- The clarinet song Squidward is seen playing at the graduation is also the song he performs in "SquidBob TentaclePants" and "No Hat for Pat."
- This is the first time Karen and Sandy work together.
- This episode marks the first time The Rake Hornpipe theme is heard since "Plankton's Regular" from season 6.
- This episode has a similar ending to "Face Freeze!" as things did not completely go back to normal by the end of the episode.
- This is the second time Plankton uses another character's DNA for one of his plans. The first time was in "Plankton's Good Eye." In that episode, Plankton uses SpongeBob's DNA and in this episode, he uses Patrick's DNA.
- This episode takes place after "Perfect Chemistry" because that is the episode where Sandy and Karen met.
- This episode might take place after "Patrick SmartPants," which would explain why Karen and Sandy didn't try to teach Patrick because Sandy knows what smart Patrick is like.
- This episode marks the second time a "One-Way Chalkboard" can be seen at the end of an episode. The first was in "New Student Starfish."
- There is a reference to "New Student Starfish" when Sandy observes Mr. Krabs and Plankton through a chalkboard, which is what Mrs. Puff did for SpongeBob and Patrick in the aforementioned episode.
- Sandy probably would've been okay even if she wasn't in her treedome because of wearing her space suit whenever she's outside.
- According to Karen, Plankton has apparently boiled his underwear at least once sometime before this episode.
- This episode premiered eight years after the premiere of "Nature Pants," "Opposite Day," "Culture Shock," and "F.U.N." in Poland and five years after the premiere of "Frozen Face-Off."
- This episode premiered in Canada on David Glen Eisley's 64th birthday and one year after "Driven to Tears" premiered in Poland and "Tutor Sauce" premiered in Germany and Poland.
- This episode shares similarities with the Angry Beavers episode "Moronathon Man."
- Several plot of this episode is similar to the Futurama's episode "The Day the Earth Stood Stupid", which involves the whole town becoming stupid, except for one or two character(s).
- When Plankton goes into Home Ec, his lips are out of sync for a moment.
- When Mr. Krabs perfects the Krabby Patty recipe, The lettuce is supposed to go on top of the patty, but Mr. Krabs says it's correct.
- When Karen carries Plankton away, he disappears and reappears for a few seconds.