- SpongeBob SquarePants
- CoolBob (debut)
- Squidward Tentacles
- Bikini Bottomites
- Incidental 73
- Unnamed band (bassist and guitarist)
- Bodyguard (debut)
- Woman fish (debut)
- Flats' dad (cameo)
- Maitre D (debut)
- Incidental 67 (cameo)
- Incidental 41 (cameo)
- Incidental 36 (cameo)
- Incidental 7 (teal and green)
- Skeptic fish (debut)
- Bryan Flounder (cameo)
- Judy (cameo)
- Other Blow Your Top Lounge customers (debut)
- Patrick Star (cameo)
The episode starts with SpongeBob whistling while working at the Krusty Krab and Squidward gets increasingly annoyed until he finally snaps back at SpongeBob. He then tells SpongeBob he is concerned about his health. SpongeBob freaks out and wants to know what's wrong with his health. Squidward says there is something wrong with the gap in his teeth, and that something can get caught in there and obstruct his breathing. So SpongeBob demands a doctor, but Squidward offers to be his dentist.
He takes SpongeBob to the kitchen and forces his two teeth together. SpongeBob notices his new change in voice as a jazz singer and starts to sing. Squidward and the customers in the Krusty Krab take notice of the singing. They crowd around to listen to his music. Squidward notices this as a chance to be cool as well. So he asks SpongeBob to join him in going to his favorite Jazz club, Blow Your Top Lounge. SpongeBob accepts the offer.
That night, Squidward barges into the club and attempts to act cool, but everyone else is not impressed. Then SpongeBob comes in and everyone is impressed at how cool he is. So they are surprised Squidward is his friend and guess if he is a friend of SpongeBob he is cool. The only skeptical person of Squidward is kicked away by him. Squidward encourages SpongeBob to start singing, and so he goes on stage. Also, Squidward follows along with his clarinet, only to be tricked to put a cork in his clarinet.
SpongeBob once again wows them with his music. But his teeth separate while singing, changing his voice back to normal, forcing Squidward to take teeth from another fish and put them in SpongeBob's mouth. The teeth fall out at the end of the performance. Squidward wants to leave the club and says to everyone that they will return again tomorrow. He takes him back to the Krusty Krab and cements his teeth back together. Then they return back to the club to play. Once again, his teeth separate. So Squidward once again cements his teeth together. Then SpongeBob allows Squidward to do a solo with his clarinet. Squidward eventually blows so hard he launches the cork out, turning back to the music the club hates.
So a bodyguard grabs him and throws him outside. Oblivious to his lack of talent but angry at being overlooked, Squidward goes back to make the gap again. He charges with a hammer only to be blown away by SpongeBob's music bubbles. He crashes into the lights and sandbags, which fall to the ground, all missing SpongeBob. That is until he runs into a sandbag still hanging and crashes to the ground. SpongeBob then realizes his gap is back. So Squidward comes out and calls him a fraud, but SpongeBob does not seem to mind now that he has his whistle back, and so he whistles.
Everyone else in the club is impressed and slams their heads to make a gap in their teeth. Squidward attempts to leave only to be stopped by the bodyguard and the manger told him to pay for the damages done to the building when SpongeBob blew the roof off with his singing.
|( ‣ ) Associated production music|
|( • ) Original music|
|( ◦ ) SpongeBob music|
• Silly Shenanigans - Nicolas Carr, Barry Anthony ["Don't you know how to keep quiet?!"]
‣ ? [SpongeBob laughs]
• Silly Shenanigans - Nicolas Carr, Barry Anthony ["Sorry for getting angry with you, SpongeBob. I'm just very concerned about your health, that's all."]
‣ Epic Struggle - Fredric Bayco ["What?! My health?!"]
‣ Clumsy A - Bernd Gesell ["It's probably nothing, forget I brought it up."]
‣ Dramatic Cue (a) - Ronald Hanmer ["What's wrong with my gap?"]
‣ Clumsy A - Bernd Gesell [Squidward tells SpongeBob his gap between his teeth can be extremely dangerous]
‣ Clumsy C - Bernd Gesell [Squidward drills SpongeBob's front teeth together]
• Hot Steel and Slide Licks 30 - Jeremy Wakefield ["And kill the whistling."]
• What's This - Nicolas Carr [SpongeBob notices his voice sounds different without the gap between his teeth]
◦ Flip Flop Fry - Tom Kenny, Andy Paley [SpongeBob singing with his new voice while cooking patties]
• A Fishy Conversation - Barry Anthony ["Hmm... How would you like to accompany me to my favorite jazz club tonight?"]
• Hot Steel and Slide Licks 35 - Jeremy Wakefield [Customers sighing]
◦ Flip Flop Fry - Tom Kenny, Andy Paley [Transition to Blow Your Top Lounge]
‣ A Brighter Day - David Luong [Audience snapping fingers at Blow Your Top Lounge]
• Hot Steel and Slide Licks 1 - Jeremy Wakefield ["Lame."]
‣ ? [SpongeBob enters at Blow Your Top Lounge/Squidward suggests SpongeBob to sing one of his tunes]
• A Fishy Conversation - Barry Anthony ["And I will accompany you on my licorice stick."]
‣ ? - Brad Carow, Nicolas Carr [Squidward starts playing the clarinet]
• A Fishy Conversation - Barry Anthony [Maitre D. puts a cork on Squidward's clarinet]
◦ Flip Flop Fry - Tom Kenny, Andy Paley [SpongeBob singing at Blow Your Top Lounge]
‣ ? ["That was so cool, it caused structural damage!"]
◦ Flip Flop Fry - Tom Kenny, Andy Paley ["But we'll be back tomorrow night to blow the road back on!"]
• Another Underwater Conversation - Nicolas Carr, Barry Anthony [Squidward fills SpongeBob's gap between his teeth with cement]
◦ Flipping Out - Tom Kenny, Andy Paley [SpongeBob singing again at Blow Your Top Lounge]
‣ ? - Brad Carow, Nicolas Carr [Squidward starts playing the clarinet]
◦ Flipping Out - Tom Kenny, Andy Paley [Squidward taken outside of Blow Your Top Lounge while SpongeBob still singing]
• What's This - Nicolas Carr [Customers murmuring]
• Tension Bits - Nicolas Carr, Sage Guyton, Jeremy Wakefield ["You see? He's not cool! He's square! He's a food-flipping fraud!"]
• Lap Steel - Nicolas Carr ["Did you hear that? My whistle is back too."]
◦ Flip Flop Fry - Tom Kenny, Andy Paley [Ending]
- This is available on the SpongeBob SquarePants Vol. 20 DVD.
- During the original American airing, it was paired up with "Breakin'," but since it has re-airing with "Dirty Bubble Returns."
- Along with "Breakin'" these episodes preceded the original American premiere of the Nickelodeon animated series Lego Jurassic World: Legend of Isla Nublar.
- The title card background is similar to those of "Culture Shock," "SpongeBob SquarePants vs. The Big One," "A Pal for Gary," and "Mimic Madness," as most of them are recolored, however, this one has the tikis' teeth being gapped.
- In British airings of this episode, the scenes where Squidward uses a drill on SpongeBob's teeth and SpongeBob drinks bubble soap are cut out because kids might imitate it. In the scene in which Squidward pushes SpongeBob's teeth together, it works instead of the teeth pushing Squidward away, and in the scene in which the screw falls loose, the screw and holes in SpongeBob's teeth are removed.
- The song SpongeBob sings to the ladies in the club after his gap opens is a song he and Patrick sung in "Scavenger Pants."
- A clip was used for a commercial from "SpongeBob's Big Birthday Blowout."
- This is one of the rare episodes where Squidward apologizes for getting angry at SpongeBob.
- The title of this episode is a popular phrase among rapid transit systems outside North America, with the most popular usage being the London Underground.
- This episode pays homage to the films that take place in the 1950s and are musicals like Ralph Bakshi's American Pop and Hey Good Lookin', Grease, Saturday Night Fever, and many others.
- SpongeBob shouting "Ladies!" when his gap breaks is a reference to late actor Jerry Lewis.
- Coincidentally, SpongeBob's personality was based on Jerry Lewis'.
- Just after Squidward screws SpongeBob's buck teeth together, SpongeBob sighs in his normal voice.
- In the shot after the close-up of Squidward saying "...then neither is SpongeBob!," SpongeBob's buck teeth are larger than usual.
- In the storyboard, Incidental 41 was incorrectly labeled as Incidental 14.
- SpongeBob's gap opening/Squidward closing the gap.
- Squidward cringing when he or SpongeBob says "best friend" to each other.
- The female waitress lemonade glasses getting broken when Squidward plays the clarinet badly.