- Eugene H. Krabs
- Sheldon J. Plankton
- Sandy Cheeks
- Patrick Star
- Karen Plankton
- Human crowd
- Incidental 114
- Incidental 104
- Incidental 6
- Incidental 37B
- Incidental 48
- Fred (normal; blue)
- Incidental 151
- Incidental 108
- Incidental 92
- Incidental 14
- Incidental 41
- Incidental 5
- Incidental 73
- Incidental 42
- Incidental 106
- Incidental 64
- Incidental 2
- Incidental 40
- Incidental 67
- Incidental 158
- Incidental 13
- Incidental 105
- Incidental 37A
- Incidental 21
- Incidental 29
- Incidental 16
- Incidental 20
- Incidental 27
- Incidental 17
- Incidental 7
- Incidental 23
- Incidental 155
- Incidental 115
- Incidental 49
- Incidental 12
- Incidental 3
- Incidental 4
- Incidental 60
- Incidental 9
- Incidental 22
- Incidental 63
- Incidental 8
- Incidental 47
- Squidward Tentacles
- SpongeBob SquarePants
- Mrs. Puff
- French Narrator
- King Neptune (mentioned)
The episode starts with Plankton getting kicked out of the Krusty Krab in another failed attempt to steal the formula. Plankton wonders how Mr. Krabs keeps on stopping his plans to steal his formula if crabs' brains are smaller than the point of a pencil, but Sandy tells him Mr. Krabs would have be as dumb as Patrick to give up the formula. Plankton gets the idea of obtaining Patrick's DNA to make Mr. Krabs dumb, so he goes to Patrick while he is sleeping to obtain it.
After he obtains the DNA, Plankton starts making Salsa Imbecilicus at the Chum Bucket. However, he accidentally gets some on him and becomes dumb as a result. The stench of the sauce goes into a cloud, causing it to rain droplets of the sauce all over Bikini Bottom. Meanwhile, Sandy comes out of her treedome, only to see that everyone has become as dumb as Patrick.
After noticing that everyone has lined up to go to the Chum Bucket, Sandy goes to Karen to ask what happened. After finding out, the two try to snap Plankton out of being dumb, but they fail. Eventually, they get the idea to start a university to make everyone normal again. Sandy and Karen get everyone to come to the university and they teach them successfully.
One Semester Later, everyone has become smart again except for Plankton, who has become the bully at the school. On Graduation Day, everyone is getting their diplomas. However, Mr. Krabs is still in the Home Ec room, perfecting the Krabby Patty. Plankton attempts to steal the patty from Mr. Krabs, but SpongeBob saves Mr. Krabs by giving him his diploma, which allows him to know not to give the formula to Plankton. The episode ends with Mr. Krabs throwing Plankton away onto Karen, who rolls into the distance.
- Karen playing a laugh track after each humiliation.
- Patrick riding a skateboard upside down.
|( ‣ ) 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 2 - Nicolas Carr, Barry Anthony [Sandy talks to Plankton.]
• Hot Steel and Slide Licks 22A - 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 17A - 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.]
• Seaweed - Steve Belfer [Sandy sees citizens acting like idiots.]
• Hot Steel and Slide Licks 4 - Jeremy Wakefield [Patrick puts a balloon in his mouth.]
• Seaweed - Steve Belfer [Krabs throwing money around.]
• New Vibe Hits 2007 - Nicolas Carr [Sandy sees a line at the Chum Bucket.]
• Hot Steel and Slide Licks 30 - Jeremy Wakefield [A fish sucks Sandy's helmet.]
• Clowning Around - Nicolas Carr, Barry Anthony [Karen explains to Sandy what happened.]
• Clowning Around Again - Nicolas Carr, Barry Anthony [Sandy and Karen trying to snap Plankton out of it.]
• Great Idea Patrick - 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.]
• Gator - Steve Belfer [SpongeBob stuffed in locker.]
• Hot Steel and Slide Licks 22A - 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.]
• Credit Card Heaven - 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.]
• SpongeBob Theme II - Nicolas Carr, 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.]
• Great Idea Patrick - 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 29A - Jeremy Wakefield [Krabs gets an A+ in acting.]
‣ The Rake Hornpipe - Robert White [Ending.]
- This episode is available on the SpongeBob SquarePants Vol. 16, Complete Ninth Season, Next 100 Episodes, and The Best 200 Episodes Ever DVDs.
- The clown wig on Squidward's Easter Island house has the same color scheme of the rainbow that was first seen in "Suction Cup Symphony."
- This episode was originally going to be called "Idiot Sauce," but the title was changed because it was deemed that it sounded "too mean."
- It may also have been because the Latin scientific term of "Salsa Imbecilicus" was more fitting, seeing as how Plankton created the sauce in a science lab.
- Despite this, there are two episodes that had "idiot(s)" in the title: "Survival of the Idiots" and "Idiot Box." Possibly, the change comes from the difference in times.
- Plankton mentions both the actual episode title and the original title.
- Other TV scheduling websites like TV Passport used the original title.
- In the Arabic dub, this episode is called "صلصة الغباء" which translates to "Idiot Sauce."
- Plankton could have just swabbed the saliva on the floor to get Patrick's DNA instead of going inside his mouth.
- Despite being the one who created the idiot sauce, Plankton seems most affected by it as he is the only Bikini Bottomite who does not regain his intelligence.
- A clip from this episode can be seen in Karen's memory bank in "Karen's Virus."
- This episode marks the first for several things:
- The first episode to play the third version of "Seaweed" since "Funny Pants" in season 4.
- The first episode where Sandy and Karen work together.
- The first appearance of the Bikini Bottom University.
- The first time "The Rake Hornpipe" is heard since "Plankton's Regular."
- The first episode to have Brian Morante as the storyboard artist. His work on the show was initially supposed to be freelance, but the crew liked his work so much that he was hired full-time.
- This is the fifth and final episode to air for the July 2016 premiere week. It is also the lowest-viewed episode in the event.
- According to Karen, Plankton has apparently boiled his underwear at least once sometime before this episode.
- Karen breaks the fourth wall by playing a laugh track after Plankton gets humiliated.
- This is the only season 9 episode where "Gator" plays.
- Plankton says that a crab's brain is smaller than the point of a pencil. In reality, it is smaller than the size of a pea.
- The clarinet song Squidward is seen playing at the graduation is also the song he performs in "SquidBob TentaclePants" and "No Hat for Pat."
- The scene of Plankton gathering Patrick's DNA has become a notorious meme due to it being surprisingly vulgar.
- When Plankton is revealed on Graduation Day to still be stupid, he has clearly gained intelligence from before starting school, as he is able to speak full sentences and supposedly bully people do what he wants. Otherwise, this is possibly an allegory to how most bullies are insecure and lack skill or intelligence themselves, therefore need to put others down to feel confident.
- This was the second episode where Plankton uses another character's DNA for one of his plans. The first was "Plankton's Good Eye." In that episode, Plankton uses SpongeBob's DNA, and in this episode, he uses Patrick's.
- This was the second episode where a "One-Way Chalkboard" can be seen at the end. The first was "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.
- In the Croatian dub, the episode's name is "Umak za idiote" which translates to "Sauce for Idiots."
- In the Russian dub, Plankton's scream after Patrick's tongue licks his butt was not dubbed.
- Also, in this version, Karen's line when she asks Plankton if he is boiling underpants was changed to socks.
- This episode has a similar ending to "Face Freeze!," as things do not completely go back to normal by the end of the episode.
- The ending is also similar to its sister episode "Pineapple Invasion," since both end with Plankton walking into the sunset, though in this episode, Karen carries him. The sunset background from the aforementioned episode is reused.
- In the Filipino dub, the scene where Patrick's tongue licks Plankton's butt was cut for inappropriate reasons.
- The fish riding a bike on the sand in a circle is reminiscent of Curly of the Three Stooges running around on the floor.
- 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 is correct.
- When Karen carries Plankton away, he disappears and reappears for a few seconds.