- SpongeBob SquarePants
- Gary the Snail
- Shelley (cameo)
- Frankie Billy
- Norton (debut)
- Female crossing guard (debut)
- Fish children
- Marching Band
- Didgeridoo player
- Patrick Star
- Mirror SpongeBob (debut)
- Lenny (orange; debut)
- Dark green fish
- Officer Johnson
- Purple leech creature (debut)
- Squidward Tentacles
- Fred (blue)
- Scooter (purple)
- Tina Fran
- Abigail Marge
- Jimmy Gus
- Nancy Suzy Fish
- Billy's mom (debut)
- Peterson Nat Tucker
- Other Bikini Bottomites
SpongeBob wakes up one morning and realizes that it is Sunday, and decides to have an ice cream "sundae" for breakfast. However, he sees he has no ice cream, and finds standard toppings like bananas and cherries to be blasé, so he instead creates a new type of sundae made from onions, ketchup, and the contents of a nearly dead potted peanut plant. Unbeknownst to SpongeBob, the result of eating the sundae is intense halitosis.
After breakfast, SpongeBob begins his Sunday to-do list, which consists of saying "Hi!" to everyone in town. Unfortunately, the townspeople are universally disgusted by the smell of SpongeBob's rancid breath and run away from him. SpongeBob is very confused by this, and asks Patrick if he notices anything wrong with him. Patrick, not having a nose, can't discern the foul odor. After running down a list of possibilities, Patrick comes to the conclusion that SpongeBob is simply ugly. SpongeBob is dismayed by this revelation, and isolates himself in his home.
Later, Patrick visits SpongeBob, who has resigned to become a hermit. Patrick tells SpongeBob the story of The Ugly Barnacle, which fails to cheer him up. Patrick then encourages him to take pride in his ugliness. It works, and SpongeBob's confidence grows, so they decide to go see a movie at Reef Cinema.
As they take their seats, all of the movie-goers still try to avoid SpongeBob, which angers Patrick and sends him into a tirade. Patrick forces the other viewers to look at SpongeBob. With every word SpongeBob speaks, the viewers panic and flee, soon leaving no one in the auditorium. Patrick gets hungry, so they go to the lobby to buy a snack. However, no one is at the counter. Instead, SpongeBob pulls some of his sundae out of his pocket and gives it to Patrick. After eating it, Patrick feels a sudden urge to use the bathroom.
While washing his hands, Patrick asks a fish next to him for some soap, but he quickly runs away. Upon finding no one will stay within his vicinity, Patrick fears he has caught "the ugly" from SpongeBob, and hides in a stall with a paper bag over his head.
Eventually, SpongeBob smells Patrick's extremely foul breath and tries to tell the rambling Patrick before shouting at him to get his attention. He then tells Patrick that it is not his appearance, but his breath which stinks, much to Patrick's relief. SpongeBob then asks what he ate, after being told it was the sundae SpongeBob made. The latter comes to the realization that they are not ugly, but simply have bad breath from the sundae.
Immensely relieved their appearance wasn't the problem, the two begin to run around shouting, "We stink!", causing their noxious breath to melt down the theater. SpongeBob and Patrick run into Squidward, looking at wigs in a window display. SpongeBob cries out in joy, "Guess what, Squidward? We stink!" as they hug him, leaving Squidward staring blankly as SpongeBob and Patrick start running away laughing and cheering.
|( ‣ ) Associated production music|
|( • ) Original music|
|( ◦ ) SpongeBob music|
‣ Hawaiian Hula - Terry Day [Opening]
‣ Lonely Violin - Dick Stephen Walter [Gary playing violin]
‣ Hawaiian Hula - Terry Day [Peanut plants]
‣ On the Beach - Kapono Beamer [SpongeBob has bad breath after finishing the sundae]
‣ Nostalgic Hawaii - George de Fretes, Jan Rap [SpongeBob saying hi to everyone]
‣ Shock (f) - Dave Hewson [Everyone runs away]
‣ Seaweed - Steve Belfer [SpongeBob finds Patrick sitting on a bench]
‣ Harry's Back - Hans Ehrlinger ["Maybe it's the way you're dressed."/"You gotta be kiddin' me.."]
‣ Steel Licks (d) - Jeremy Wakefield [Reflection test]
‣ The Nightmare Begins (a) - John Devereaux [SpongeBob asking people if he is ugly]
‣ Hawaiian Link (b) - Richard Myhill ["I'm ugly...!"]
‣ The Last Judgement - Peter Lea-Cox [Organ music]
‣ Monster Chords (c) - Peter Lea-Cox [Organ music]
‣ A Day by the Sea - Dick Stephen Walter [The Ugly Barnacle]
‣ Hawaiian Cocktail - Richard Myhill [Spiraling]
‣ Me for You - George Callert ["Okay, now, say it."]
‣ The Land is Ours - Gregor F. Narholz [SpongeBob saying he is ugly and proud]
‣ Hawaiian Link (a) - Richard Myhill [Movie theater exterior]
‣ Legends of Hollywood (a) - Ron Goodwin ["Pardon me, ugly sponge coming through."]
‣ Hawaiian Link (b) - Richard Myhill ["I'm not always as confident as I look."]
‣ On Fire - Gregor F. Narholz ["What is wrong with you people?!"]
‣ Vibe Link (b) - Richard Myhill ["Oh wait, Patrick, I just remembered."]
‣ SpongeBob Closing Theme - Steve Belfer, Nicolas Carr [SpongeBob saved some of the sundae]
‣ Samoa Hotel - Salvatore Assenza, Franco Zauli [Inside the bathroom]
‣ Shock (c) - Dave Hewson ["I caught the ugly!"]
‣ Hawaiian Breeze - Jon Jelmer [Patrick with a bag over his head]
‣ Shock (p) - Dave Hewson ["You gave me the ugly!"]
‣ Seaweed - Steve Belfer [SpongeBob smells Patrick's breath]
‣ Vibe Link (b) - Richard Myhill ["Sundae..."]
‣ Hawaiian Link (a) - Richard Myhill ["We're not ugly, we just stink!"]
‣ Chief Taravana - Kapono Beamer [Ending]
- This episode is available on the Nautical Nonsense and Sponge Buddies, Complete 2nd Season, The First & Second Seasons, The Best 200 Episodes Ever, It's a SpongeBob Christmas! (Blu-ray), Complete Second Season, and First 100 Episodes DVDs.
- This episode is also available on the Nautical Nonsense and Undersea Antics Volume 1 VHS's.
- This is the first season 2 episode in airing order.
- This episode premiered in Canada on January 26, 2001.
- Patrick mentions that he does not have a sister in this episode. However, this is later proven false by the episode "Big Sister Sam," where he is indeed revealed to have a sister.
- A few scenes from this episode have become popular internet memes. These include:
- The scene where Patrick holds SpongeBob up and shouts "Look at it!" This meme is called "Patrick Wants You To Look At It," where something else replaces SpongeBob.
- The Ugly Barnacle story told by Patrick.
- The shot where Fred is seen screaming "Deuueaugh." Several videos include him screaming this phrase for long periods of time. There are also videos of the scream in multiple languages.
- This is the first episode where Patrick's eyebrows are "Z" shaped. With the exception of "Big Pink Loser," all future episodes will feature this design instead of the original sideways "M" shape.
- In the DVD commentary, it is mentioned at the end of this episode that Squidward had a deleted line. After SpongeBob and Patrick hug him and run away, he would say "Ugly and smelly, two for one," but it was cut due to the whole screen fading to black at the end.
- The giant calendar that SpongeBob is flung into by his bed at the beginning is a gag reused from "Boating School."
- Irony: The fish could've just told SpongeBob his breath stinks.
- "My leg!:" The marching band gets irritated with the stench of SpongeBob's breath after they bump into buildings that they got thrown into.
- This episode has a pretty high kill count:
- Norton's body layers fall apart.
- SpongeBob's reflection commits suicide by smashing himself with a hammer.
- Two fish commit suicide by reeling themselves up with a hook.
- SpongeBob causes a car to explode, killing the driver.
- The Ugly Barnacle was so ugly that everyone died. Though this is only a story.
- SpongeBob's bad breath causes two fish to go belly-up in the movie theater.
- Another fish gets her face destroyed by SpongeBob's breath.
- There is an online game based on this episode titled Stinky Swagger.
- This and "Bossy Boots" are the first episodes not to appear in chronological episode number order. Instead of airing after "Your Shoe's Untied"/"Squid's Day Off," which would be chronologically in order of episode number, it had first aired after "Hooky"/"Mermaid Man and Barnacle Boy II."
- This episode marks the first time that a "Steel Licks" track plays.
- This is the first episode where "Chief Taravana" plays in its normal pitch.
- At the beginning of the episode's audio commentary, it is revealed that the episode was originally going to start out with SpongeBob going out to buy every gallon of ice cream in town and he did not know the brand of ice cream he bought was onion; he then eats it and gets bad breath. But they later decided that he would make his own sundae with ketchup, raw onions, and peanut plants with dirt.
- This episode is the first one in season two to use the Crowd Scream sound effect, the others being "Wormy" and "The Smoking Peanut."
- A snippet from Patrick's phrase "Maybe it's the way you're dressed." is widely believed to have been used in Undertale as a voice clip for Sans.
- This episode takes place after "Library Cards" because Patrick knows SpongeBob's library and reading, and in that episode he didn't.
- After SpongeBob finishes his sundae, he says to Gary, "You know what they say, Gary... I'm easy like Sunday morning," a reference to the chorus of The Commodores' 1977 song "Easy."
- The shot with SpongeBob playing the organ and wearing a mask is a reference to The Phantom of the Opera.
- The Ugly Barnacle may be a reference to The Ugly Duckling by Hans Christian Andersen.
- The glasses SpongeBob wears in this episode are a parody of Groucho Marx.
- After SpongeBob goes from his bedroom to his kitchen to make the sundae, when he opens the door, his bedroom wallpaper is shown instead of his living room's; SpongeBob's bedroom is not located next to his kitchen.
- A brief screen jump glitch can be seen and heard during the title card sequence. This has occurred on Nicktoons and Nickelodeon airings of this episode for several years.
- When Patrick sees SpongeBob in his house, playing the organ, SpongeBob has a mask on, but after SpongeBob turns around and Patrick lifts him up, the mask is gone.
- When credited as animation director, Edgar Larrazábal's last name is misspelled as Larrazabla. This was fixed on Nickelodeon and Nicktoons USA in early 2005.
- At The Reef, SpongeBob and Patrick first sit in the front row. But later, when Patrick lifts SpongeBob, they appear to be in the middle row.
- When SpongeBob talks to the blue woman in the red dress, the fish in the background change colors from blue to green to red.
- When Patrick says, "Don't worry about him, SpongeBob," the fish turns back to green.
- At The Reef, when SpongeBob and Patrick get into the theater, it is in a wide-shot and Fred is at the end of the front row. However, when SpongeBob and Patrick pass him, he is at least two seats in and next to Dave.
- In all Nickelodeon USA airings of this episode and iTunes version, SpongeBob walks up to a building and says, "Hi, building!" which causes the building to flee from SpongeBob's breath. He goes up to Patrick and says, "I just don't get it!" and Patrick says, "I don't either."
- On all DVD releases, the Nautical Nonsense VHS tape, the Nick Scene It? DVD game, Canadian airings on YTV and Nickelodeon Canada, Polish airings, UK airings, and Australian airings, the scene instead goes like this:
- SpongeBob: (walks up to a building and waves) I just don't get it! (the building flees)
- Patrick: (offscreen) I don't, either. (SpongeBob walks up to Patrick; the rest of the scene goes as normal, resulting in the same lines being repeated). According to the audio commentary on the Season 2 DVD, this was a sound mixing error. The music also repeats itself incorrectly at that point. It's made obvious since SpongeBob's mouth still clearly says the intended line. However, the closed-captioning on the Nautical Nonsense and Sponge Buddies and Season 2 DVDs still use the original correct line. But on The First 100 Episodes DVD, the closed-captioning have been updated to match the incorrect audio.
- At The Reef, when SpongeBob and Patrick arrive in the theater, it is in a wide-shot and Tom is next to the red fish, Harold. However, when SpongeBob and Patrick get to Harold, he is sitting next to the red-haired fish.
- Also upon arriving, almost every seat has someone in it, but when SpongeBob gets to the front row, very few seats are filled.
- At several parts in the episode, SpongeBob does not have the rancid breath cloud.
- In the bathroom, when SpongeBob first opens the stall door, Patrick's reflection does not move.
- For a split second when SpongeBob yells "Patrick!," a majority of his holes are missing. However, the reflection on the floor has holes.
- People running away when SpongeBob talks due to his horrible breath.