- Karen Plankton
- Sheldon J. Plankton
- King Neptune (mentioned)
- Squidward Tentacles
- SpongeBob SquarePants
- Clay (cameo)
- Nat Peterson (cameo)
- Norma Rechid (cameo)
- Sandy Cheeks (cameo)
- Butterflies (mentioned)
- Patrick Star
- Amoeba (text)
- Harold "Bill" Reginald
- Nancy Suzy Fish
- Shelly Fishbowl
- Taylor Fishbowl
- E.M.I.L.P. (debut)
- ATM (mentioned)
SynopsisPlankton walks to the Chum Bucket stinking with the stench of "failure," as he calls it, and Karen is in a very happy mood. Karen then smells Plankton and gives him a bath, taking off his skin, which is revealed to be his clothes. After he's washed, Plankton learns that it was his and Karen's wedding anniversary and that Karen got him a copy of the Krabby Patty secret formula for his present, but he can't have it until he gets her a present.
Plankton is crying on the road and SpongeBob hears him crying. He sniffs like a dog and soon runs into Plankton. He tells SpongeBob the news, and SpongeBob yells to all of Bikini Bottom that there's a "Love Emergency." SpongeBob then tells Plankton that his present has to come from the heart, and he suggests a serenade. Plankton then remarks that he cannot sing, and SpongeBob takes him to the pineapple and works on Plankton's vocal cords. Plankton sings so high that he breaks the glass Squidward was drinking out of his juice and Sandy's helmet breaks while she was walking then she runs back to her treedome for air. Then, Plankton goes off to serenade Karen.
Plankton walks into the Chum Bucket and starts singing a mariachi-style song, and SpongeBob and Patrick play guitars in the background, wearing Mexican-style clothing and mustaches. Plankton also shakes maracas. Karen cries when it is over, and then she starts uploading the Krabby Patty secret formula. SpongeBob is mad at this, so he unplugs what he thinks is Karen, but was just the coffee maker. Karen finally uploads the formula, but she starts crying again, and she breaks down and shorts out, leaving Plankton still without the secret formula, making him confused. She then shuts down, and the E.M.I.L.P (Emergency Mother-In-Law Program) uploads and starts nagging, saying that Karen could have married the ATM, someone with money.
|( ‣ ) Associated production music|
|( • ) Original music|
|( ◦ ) SpongeBob music|
‣ Emotion Blues - Francois Fournet, Eric Gemsa [Plankton comes home]
‣ Hawaiian Cocktail - Richard Myhill ["And now the smell of defeat so deeply penetrates my soul..."]
‣ Darting Around - Harry Bluestone [Karen cleaning Plankton]
‣ Steel Licks (d) - Jeremy Wakefield ["It's not enough to mask the ugliness I feel inside."]
‣ Darting Around - Harry Bluestone ["Did I miss a spot?"]
‣ Tension Bits - Nicolas Carr, Sage Guyton, Jeremy Wakefield [Plankton gets angry/Plankton still getting angry]
‣ Fantasy Princess [#52] - Harry Bluestone, Emil Cadkin ["It has something to do with you asking a certain someone..."]
‣ Vibe Sting - Nicolas Carr ["What?"]
‣ Bridal Chorus - Richard Wagner ["We each wear rings in memory of this moment."]
‣ Steel Sting - Jeremy Wakefield ["It's our wedding anniversary!"]
‣ Parting of the Clouds - Nicolas Carr [Karen got Plankton the secret formula]
‣ Happy Sack Shanty - Michael Bolger, Nicolas Carr [Karen explains how she got it through a flashback]
‣ ? - Nicolas Carr [Plankton kissing the formula bottle]
‣ Steel Sting (n) - Jeremy Wakefield [Karen wants a gift from Plankton]
‣ Hello Blues - Sage Guyton, Jeremy Wakefield ["And that's how I got my head stuck in the fry vat."]
‣ Accusation - Gerhard Trede [Plankton groaning]
‣ Vibe Sting - Nicolas Carr ["Plankton?"]
‣ Hawaiian Cocktail - Richard Myhill [Plankton tells SpongeBob about his wedding anniversary]
‣ Chasey Racey - Norman Dane [love emergency]
‣ Goofy Conversation - Nicolas Carr, Barry Anthony ["There's only one thing to do."]
‣ Sport Fanfare - Gerhard Trede ["That's it!"]
‣ Cartoon Sting 1 - Plankton telling SpongeBob about Karen
‣ Unknown Hawaiian Sting (a) - Jeremy Wakefield [Transition to next scene]
‣ Unknown Track 68 - Sandy's helmet breaks
‣ Climb to Altitude - Trevor Duncan ["Oh, you are ready!"]
‣ Tiki Rapido - Lionel Wendling ["This is it, Plankton."]
‣ Unknown Track 54 - Nicolas Carr ["Ah, love."]
‣ Lonely Heart's Club (a) - David Bell, Otto Sieben [Plankton returns home]
• Oh, My Karen - Luke Brookshier, Eban Schletter [Plankton sings]
‣ South Pacific Island II - Victor Cavini ["That was so beautiful!"]
‣ Crime and Danger Sign #3 - Delle Haensch, Hans Conzelmann ["The Krabby Patty formula?!"]
‣ Dramatic Sea Battle - Gerhard Trede ["I am so fired."]
‣ Victory of Love - Gerhard Trede [Karen crying]
‣ Steel Sting (b) - Jeremy Wakefield [computer shorts out]
‣ Skipping to School - Sage Guyton, Jeremy Wakefield [Emergency Mother-In-Law Program]
- This episode is available on the Triton's Revenge, Season 6 Volume 2, Complete Sixth Season, and Next 100 Episodes DVDs.
- As of June 18, 2019, The Internet Movie Database (IMDB) gives this episode a rating of 7.4/10 based on 187 ratings by users. TV.com users give this episode a rating of 9.1/10 based on 8 votes.
- "Kind of obscure, but one of the few episodes to focus on the 'honeymooners-like' marriage of Plankton and Karen (just a microorganism and his computer wife tryin' to get by). I love how Plankton swings between henpecked husband and world-conquering megalomaniac."
- This was the third episode to premiere during Nickelodeon's "Deep Sea Danger Zone" marathon.
- Karen is upset with Plankton for not having an anniversary gift for her, but in the end, she is the one who fails to give the other an anniversary gift. This isn't necessarily her fault however, since she got waterlogged by her "tears."
- On the Nickelodeon schedule, this episode is called "Green Anniversary."
- SpongeBob knows what butterflies are in this episode, but not in "Wormy." Therefore, this episode must take place after that one.
- On the Complete Sixth Season and Season 6 Volume 2 DVDs, this was the final episode, but it was not the last episode season 6 episode in airing or production order.
- This episode takes place before "Atlantis SquarePantis," The SpongeBob Movie: Sponge Out of Water, and Plankton's Holiday Hits because Plankton sings in those.
- In "Enemy In-Law," Plankton says that he bought Karen. Yet in this episode, he says that he built her.
- This episode reveals that Karen is a Mark II Surplus UNIVAC with 256 gigabytes of RAM.
- SpongeBob presses the keys Ctrl, Alt, and Del. Karen is most likely based on a Windows system, since these keystrokes either allows the user to log on, opens a Task Manager, or opens a screen with options like Task Manager on a real Windows computer.
- Karen's "Error" screen is a parody of blue screens usually found when a computer is malfunctioning.
- At the beginning of the episode, Karen has the secret formula printed out in a bottle. However, at the end, Karen had to print it out.
- When SpongeBob attempts to Ctrl-Alt-Del Karen, the keyboard keys are white. When Karen begins to short circuit, they are red.
- SpongeBob wore a mustache during the "Oh, My Karen" song, but when everyone else says "Awww...", he no longer has a mustache.