- SpongeBob SquarePants
- Eugene H. Krabs
- Squidward Tentacles
- Sheldon J. Plankton
- Ray Ray (debut)
- Mini Brain Plankton (debut)
- Karen Plankton
- Lily Plankton
- French Narrator
- Mr. Krabs' grandma (cameo)
- Daydream Bikini Bottomites
- Dream Lily Plankton (debut)
- Dream Squidward (cameo)
- Dream Sandy (cameo)
- Dream Mr. Krabs (cameo)
- Dream SpongeBob (cameo)
- Dream Plankton (cameo)
- Dream Patrick (cameo)
- Dream Incidental 116 (cameo)
- Dream Fred (cameo)
- Dream Incidental 41 (cameo)
- Dream Incidental 73
- Dream Incidental 37B
- Dream Incidental 31
- Dream Incidental 64
- Dream Incidental 2 (purple)
- Dream Old Man Walker
- Dream Incidental 23
- Dream Incidental 85
- Dream Incidental 155
- Dream Incidental 8
- Dream Incidental 3
- Dream Scooter
- Dream Incidental 46
- Dream Incidental 12
- Dream Incidental 49
- Dream Incidental 154
- Dream Incidental 37A
- Dream Incidental 36
- Dream Incidental 22
- Dream Incidental 47
- Dream Incidental 21
- Dream Incidental 14
- Dream Incidental 13
- Dream Incidental 45
- Dream Sandals
- Dream Incidental 63
- Dream Incidental 104
- Dream Incidental 5
- Dream Incidental 48
- Dream Incidental 27
- Dream Incidental 118
- Dream Incidental 40
- Dream Incidental 42
- Dream Incidental 105
- Dream Incidental 93
- Dream Incidental 68
- Dream Incidental 67
- Dream Incidental 6
- Dream Incidental 30
- Dream Incidental 30
- Dream Incidental 115
- Dream Incidental 107
The episode starts off with Plankton pampering Karen and giving her a mud bath. As Plankton and Karen are about to kiss, Karen's screen turns off and is replaced with a call from Plankton's grandmother. It turns out that Plankton promised to own the Krusty Krab by her 90th birthday, and her birthday is tomorrow and she is coming to visit the Krusty Krab. Because of this, Plankton has to lie and keep the lie going when she visits. Plankton explains to SpongeBob and Mr. Krabs the situation, and after explaining it in a sincere way, SpongeBob and Mr. Krabs agree to give the Krusty Krab a Plankton-themed makeover.
The next day, Plankton's grandma visits the now-Plankton-themed Krusty Krab to take a look. While Plankton is trying to force SpongeBob, Mr. Krabs, and Squidward into the scheme, Grandma Plankton starts to develop a crush on Squidward. Grandma Plankton introduces herself as Lily and wants to have a Plankton Patty, so SpongeBob makes one for Lily and forces Squidward to chew it for her.
The scheme finally works out until Lily wants a picture with the Secret Formula. Plankton does his sincere face and Mr. Krabs hands over Lily the formula. As they start to take a picture, Lily flies away with a jetpack. Mr. Krabs gets angry at Plankton for creating a plan to steal the formula, but Plankton did not know a thing about this; however, Plankton, thinking he won, thinks he can rule the fast food industry with Grandma, but Lily states she is not sharing the formula and drops Plankton and flies away to the retirement home.
Finally winning, Lily daydreams her idea of forcing Squidward to be her ally while the other citizens have to fight over the patties Lily throws. However, before she can open the bottle, Lily goes to sleep, so Mr. Krabs get the formula back and Plankton gives Lily prune juice, wishing Lily happy birthday, ending the episode after Lily slaps Plankton with her purse.
- Plankton making his sincere face.
- Lily smacking people with her purse.
- Lily flirting with Squidward.
|( ‣ ) Associated production music|
|( • ) Original music|
|( ◦ ) SpongeBob music|
• Earl's Revenge - Sage Guyton, Jeremy Wakefield [Title card]
‣ Esta Noche (b) - Hans Ehrlinger [Plankton pampering Karen.]
• Nude Sting - Nicolas Carr ["Grandma?!"]
• Light Conversation 1 - Nicolas Carr, Barry Anthony [Plankton's grandma talks to Plankton.]
‣ Drama Link (b) - Hubert Clifford [Plankton thinks about lying to his grandma.]
• Light Conversation 1 - Nicolas Carr, Barry Anthony [Plankton claims to his grandma he owns the Krusty Krab.]
‣ Esta Noche (b) - Hans Ehrlinger ["Now bring back Ray-Ray."]
• Hot Steel and Slide Licks 9 - Jeremy Wakefield ["What am I gonna do, Karen?"]
• Silly Bob Conversation 2 - Nicolas Carr, Barry Anthony [Karen kicks Plankton out of the Chum Bucket.]
• Jovial Pirate's Jig - Michael Bolger, Nicolas Carr [SpongeBob playing with the signal of the Krusty Krab.]
• Hot Steel and Slide Licks 15 - Jeremy Wakefield ["SpongeBoob, you gotta help me!"]
• Humorous Conversation - Nicolas Carr, Barry Anthony [Plankton explains his situation to SpongeBob.]
‣ Hot Steel and Slide Licks 30 - Jeremy Wakefield [One pathetic sob story later...]
‣ Tabu - Daryl Griffith [Plankton's sincere face.]
• Lap Steel - Nicolas Carr [SpongeBob gets happy.]
• Salty Krab Jig - Michael Bolger, Nicolas Carr [Krabs swallows the Krabby Patty secret formula.]
‣ Hot Steel and Slide Licks 39 - Jeremy Wakefield ["Pronto!"]
• You're Nice - Sage Guyton, Jeremy Wakefield [SpongeBob and Squidward modifying the Krusty Krab for Plankton's grandma.]
‣ Stupid Cupid - Ronald Hanmer [Plankton's grandma arrives at the Krusty Plankton.]
• Hot Steel and Slide Licks 17 - Jeremy Wakefield [Squidward sleeping.]
‣ Co Co Baby (a) - Gil Flat [Plankton's grandma falls in love with Squidward.]
• Hot Steel and Slide Licks 10 - Jeremy Wakefield ["Alright, lady, I don't normally say this, but get off my nose."]
‣ Pepito from Tampico (a) - Otto Sieben, Ronald Sekura ["So, Grandma Plankton, where have you been all my life?"]
‣ Kitsch Comedy - Peter Jeffries [Grandma Plankton at the kitchen.]
• Hot Steel and Slide Licks 1 - Jeremy Wakefield [SpongeBob, Krabs, Squidward and Plankton juck.]
• A Simple Conversation 1 - Nicolas Carr, Barry Anthony ["You really are a master chef."]
• Fooling Around 2 - Nicolas Carr, Barry Anthony [Plankton's grandma wants a photo of her with the secret formula.]
‣ Tabu - Daryl Griffith [Plankton shows his sincere face to Mr. Krabs again.]
• Fooling Around 2 - Nicolas Carr, Barry Anthony ["Fine."]
‣ Target - Hans Ehrlinger [Plankton's grandma takes off with the secret formula.]
‣ Epic Struggle - Fredric Bayco ["Why? Why did I lie?"]
• Hot Steel and Slide Licks 2 - Jeremy Wakefield [Grandma Plankton returns to Shady Shoals with the secret formula.]
‣ ? [Grandma Plankton's world domination daydream.]
• Aloha Lui Lui - Nicolas Carr, Sage Guyton, Jeremy Wakefield [The ending]
- This episode is available on the SpongeBob SquarePants Vol. 18 and The Complete Eleventh Season DVDs.
- The title card is strikingly similar to that of "Bucket Sweet Bucket."
- "My leg!:" Everyone fighting for a Krabby Patty.
- This is Lily Plankton's first appearance since "Gramma's Secret Recipe."
- Her name is revealed in this episode.
- Several parts of this episode would later return in the season 13 episode, "Lockdown for Love:"
- Plankton's outfit and his alter ego as Ray Ray.
- Karen's "kissy face" screensaver (although it also reappeared in "Bottle Burglars").
- Plankton's "sincere face" would later reappear in the season 12 episode, "Karen's Baby."
- The title is a play on the English idiom "mum's the word."
- On the Galley Grub sign, "Krabby Patty" is misspelled as "Krabby Pattie."
- During the scene with all of the Bikini Bottomites groveling to Lily, red numbers appear on the screen for a second.
- Also during that scene, Mr. Krabs' eyelashes are missing.