- SpongeBob SquarePants
- CoolBob (single appearance)
- Squidward Tentacles
- Bikini Bottomites
- Incidental 73
- Unnamed band (bassist and guitarist)
- Bodyguard (single appearance)
- Woman fish (single appearance)
- Flats' dad (cameo)
- Maitre D (single appearance)
- Incidental 67 (cameo)
- Incidental 41 (cameo)
- Incidental 36 (cameo)
- Incidental 7 (teal and green)
- Skeptic fish (single appearance)
- Bryan Flounder (cameo)
- Judy (cameo)
- Other Blow Your Top Lounge customers (single appearance)
- Patrick Star (cameo)
At the Krusty Krab, SpongeBob is whistling while working, 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 is 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, but this causes SpongeBob's voice become deeper and more smooth-sounding. 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 person skeptical 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 into putting 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 and shatter 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 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.
A bodyguard then 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 they slam their heads to make gaps in their teeth. Squidward attempts to leave, only to be stopped by the bodyguard and the manager tells him to pay for the damages done to the building when SpongeBob blew the roof off with his singing.
- 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.
|( ‣ ) Associated production music|
|( • ) Original music|
|( ◦ ) SpongeBob music|
• SpongeBob Theme II - Nicolas Carr, Sage Guyton, Jeremy Wakefield [Title card]
• Unknown Goofy Cue - Nicolas Carr, Barry Anthony ["Don't you know how to keep quiet?!"]
‣ ? [SpongeBob laughs]
• Unknown Goofy Cue - 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 - Nicolas Carr, 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]
• Jazz at the Jellyfish Club - Nicolas Carr, Brad Carow [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 - Nicolas Carr, Barry Anthony ["And I will accompany you on my licorice stick."]
‣ ? - Brad Carow, Nicolas Carr [Squidward starts playing the clarinet]
• A Fishy Conversation - Nicolas Carr, 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!"]
• A Fishy 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 episode is available on the SpongeBob SquarePants Vol. 20 and The Complete Twelfth Season DVDs.
- During the episode's 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.
- This is the last episode that was pitched to Stephen Hillenburg during his lifetime.
- 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."
- A clip was used for a 2021 Paramount+ commercial.
- In this episode, Squidward acts nicer and kind to SpongeBob making him cooler.
- The title of this episode is a phrase among rapid transit systems outside North America.
- SpongeBob shouting "Ladies!" when his gap breaks is a allusion to late actor Jerry Lewis. 
- This episode has some references to the Jerry Lewis film The Nutty Professor.
- The title's name also came from the mission from the 2011 FPS game Call Of Duty: Modern Warfare 3.
- 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.