Spontaneous Choreography

We've all seen Crowd Songs. A crowd of random people spontaneously burst into a choreographed song and dance number. A pair of red fire trucks pull in from opposite ends of the street and start spraying arcs of water over the crowd to make a rainbow. A flock of animated sparrows flying overhead decide to drop down and whistle a melody. The Big Bad might even wander out of his lair to do a little number with a cute kid. But how is this possible? Spontaneous Choreography is the ability for fictional characters to tap into a pseudo-hive mind and perform amazing choreography with little to no practice.

It is not restricted to the Crowd Song either. Sometimes, the dance has been planned in advance, for instance in a school-sponsored dance competition, but the heroes have had no time to practice while on their adventure. No problem, just huddle up for a few seconds, and you have an instant dance routine.

It might not even be a dance. Ten seconds left in double overtime? No problem, let's go for that trick play we've only practiced once. It's bound to work. And it always does.

In short, this trope is for anything that has all the trappings of a crowd song, but without the crowd and not always with a song.

Compare Summon Backup Dancers, where the participants/dancers in question are called from out of sight.

Film

 * From Not Another Teen Movie: "Who would've guessed that everyone in school was a professional dancer?"
 * Spider-Man 3: Peter's dance routine at the jazz bar
 * Footloose where they do a similar whole school dance and everyone can dance despite being from a town/county where dancing is illegal.
 * Bollywood films generally have dance numbers that work like this trope. There are several in Bride and Prejudice.
 * Animated example: In The Return of Hanuman musical sequence "Aasman Ko Chhukar", tourists, pirates, animals, even the Statue of Liberty dances.
 * The opening of Hair features a Crowd Dance.
 * In Ferris Buellers Day Off, Ferris manages to get an entire street dancing to "Twist and Shout".
 * Woody Allen's Everyone Says I Love You has this for pretty much all of its musical numbers (whether the dancers/singers be jewlery store clerks, hospital nurses or even ghosts), though the main singers are intentionally not the best singers in order to add a bit of realism to the numbers.
 * In the Blues Brothers film, the crowd outside the music store breaks out into spontaneous dance once Ray Charles starts up Shake A Tail Feather. But then, it's Ray Charles, so its sort of expected.
 * Lampshaded in Enchanted, as Robert is the only one who finds it odd that everyone is spontaneously dancing and singing in the middle of Central Park.
 * Alvin and the Chipmunks: The Squeakquel: After escaping Ian, the six chipmunks arrive at the singing competition. After a quick huddle, they break out into a perfectly choreographed dance routine that none of them had ever done before.
 * Clerks II had one of these with that Jackson 5 song.
 * Sister Act 2 also had one in that the kids had been practicing a big traditional choral presentation, but then at the last minute when faced up against a big-time school that did the same thing better than they could have, turn it into a mixed-style free-for-all version of the same basic song. Note that the accompanying music also keeps up with the different style changes, even though they just decided to do it this way a few minutes prior.
 * In The Mask, the title character and Tina do a dance number together in the club without any practice. Justified because of the Mask's magical abilities.
 * Not to mention a big dance number with a squad of police. At one point a woman doing a solo manages to express with her eyes that she's just as confused by this development as anyone else, and is rather freaked out by the fact that her body is doing this without her say-so.
 * In South Park Bigger, Longer and Uncut, Big Gay Al is talked into doing a musical number by the crowd. Big Gay Al says "Oh, but we haven't rehearsed!". The "I Feel Super" number follows.
 * The Fisher King starring Robin Williams: As Parry, Williams's character, loses himself in a romantic reverie, the buzzling crowd in New York Central Station turns into a grand ballroom party. Justified as it's an Imagine Spot.
 * Monty Pythons the Meaning of Life justifies this (not outrightly though) with the, er, abundance of sons and daughters.
 * Tank Girl. During the "Let's Do It" Crowd Song number in Liquid Silver.
 * Parodied in Shaolin Soccer, when Sing leads the customers at a rice cake stand in a spontaneous and wholly incongruous homage to Thriller. Before the singing can begin, the shop owner screams at them, and they instantly return to their seats and continue eating as if nothing had happened.
 * Thirteen Going On Thirty: . Jenna starts dancing to Thriller, and everyone at the party remembers and executes the choreography perfectly.
 * In Five Hundred Days of Summer, after Tom sleeps with Summer he initiates Spontaneous Choreography.
 * The most Egregious example most likely can be found during the 10 minute dance number at McDonalds in Mac and Me.
 * Beetlejuice - the Maitlands' ghostly powers make the Deetze's dinner party get up and dance to Harry Belafonte's " Banana Boat Song".
 * Justified of course, since it was supernatural forces at work
 * In the second Teenage Mutant Ninja Turtles film, the climactic fight spills into a club where Vanilla Ice is performing. After a brief chat with his backup dancers, he launches into what's apparently an entire improvised rap with perfectly matched dancing about the fight.
 * In the original Step Up Tyler and Nora go to a party and Nora's entire class breaks into Spontaneous Choreography. This troper thought it was apparently a school dance because Tyler seemed to be the only one who didn't know what to do.
 * The Muppets: Pops up as Gary and Walter walk to the school to pick up Mary, then as the three walk to the bus stop.
 * Evidently this is exhausting in-universe. When Mary looks out the window at Walter after saying it is fine that he's coming to LA you can see the townspeople who danced along with them lying around, exhausted. Then once they leave town, everyone collapses.

Literature

 * Lampshaded in Terry Pratchett's Discworld novels. Specifically, Captain Carrot is the kind of heroic protagonist with such charisma that, in his girlfriend's words, if he chose to start singing some sort of song like "My town" half the people in the street would join in and dance with him despite not possibly being able to know the dance steps.

Live Action TV
"Gangleader: Whoa, whoa, whoa! What the hell is this? imitates "Cobra" hand motion What are you doing?
 * Characters in Glee seem to pull this off from time to time. Most of their numbers are rehearsed, but sometimes, as in sectionals, one character get the others to follow their lead and everything goes perfectly.
 * The Buffy the Vampire Slayer episode "Once More with Feeling". A Demon Did It.
 * The "Nothing Suits Me Like A Suit" routine from How I Met Your Mother. Justified as it's a Dream Sequence / Imagine Spot.
 * Also in the seventh season premiere, during Barney and Robin's passionate dance. This one isn't a character's Imagine Spot like "Nothing Suits Me Like A Suit," but since the entire show is made up of Future!Ted's first- and second-hand memories, it could be explained as his Imagine Spot.
 * Crosses over with a Crowd Song in Mongrels with Everyone Loves A Lesbian''.
 * In Community episode Interpretive Dance Britta and Troy are able to pull off an improved dance duet seamlessly.
 * Justified in Kamen Rider Den-O, where making people spontaneously start breakdancing is explicitly stated to be one of Ryutaros' powers.
 * Norm MacDonald lampshades this in a Saturday Night Live sketch.

Colin: We're being Cobras.

Gangleader: Ah, that's it! What is up with you guys?

Mark: What? He started singing, then he started singing, then he started singing, so I started singing. It happens.

Gangleader: No, it does not happen. This was clearly choreographed.

Dan: No. He was dancin', and I saw what his legs were doin', so I kinda copied it, like this..."


 * Subverted in the Its Always Sunny in Philadelphia episode "High School Reunion, Part 2". The gang decide to wow all their former classmates with a dance routine, with perfect choreography and every boy band music video trope you can think of, and they pull it off, instantly becoming the most popular people at the party... and then we see what's actually going on: five very drunk people stumbling aimlessly around a dance floor, sweating like pigs, while the audience cringes in open-mouthed embarrassment.

Tabletop Games
"762. Fighter can't put points in Perform just so he can hammer dance after each fatal critical hit.
 * Things Mr. Welch Is No Longer Allowed to Do In An RPG has Mr. Welch looking for an excuse to break out into song or dance.

940. I will not abuse the Exemplary virtue to set up highly choreographed dance routines with random crowds.

1120. Even if I’m in charge I can’t order the Assault Lance to perform West Side Story dance routines."

Web Comics
"HEY I thought everyone was going to start singing! I hate you all."
 * Did Marten and Dora just have sex?
 * In Bad Machinery Lottie tries to do this, but despite the Mass Hypnosis of the student body, finds that no one joins in.

Web Original

 * Muppet Viral Videos: Apparently, the Muppets' rendition of Bohemian Rhapsody resulted from a otherwise unrelated video-chat conference.

Western Animation
"Edna: Should we follow him?
 * Used and lampshaded in Futurama. During Fry's holophoner concert, the Robot Devil interrupts and takes the musical on an entirely different course. Nevertheless, everyone, even the crowd, is able to stay perfectly in tune. Lampshaded when Zoidberg sings, in tune with the beat no less, "I can't believe everybody's just ad libbing!"
 * Takes a more realistic turn in Total Drama World Tour. While they don't dance in every song, the times that they do it's very simple and predictable so the other contestants would be able to catch on(like Alejandro holding Bridgette's hand in 'Before We Die' prompted everyone to make a big circle by holding hands,) or in songs like Leshawna's 'Sisters' the other two dancers aren't in-time with each other so it looks more real.
 * TDWT does do this quite well. There are even times where you can see the contestants looking at each other so they can suddenly think of moves (like Lindsay and Bridgette in 'Come Fly with Us.' Other times, in 'What's Not to Love?' Courtney said before the song started that she was going to dance in the song, so Owen, D.J., and Leshawna just took after her.
 * Played with in an earlier episode of The Simpsons, where the whole town joined in on a salesman's song about the benefits of having a monorail. Homer sang on after the song ended, and immediately realised his mistake.
 * This happens again in a later episode where the Simpsons sing about the Kwik-E-Mart with Apu. Each family member (plus Apu) sing lines that ends in a rhyme with "Kwik-E-Mart," but Homer accidentally begins with it and interrupts it mid-line with his trademark grunt.
 * And again with those who are gathered to tear down the burlesque house and people sing 'We Put the Spring in Sprinfield' ... except Marge who was out renting the bulldozer.
 * Subverted in "Special Edna", where Homer starts singing a song about a pie, complete with musical-style choreography... which takes him out of shot, and the camera holds on the rest of the family, who don't move a muscle.

Marge: I'm on vacation."


 * Home Movies - facing a performance in a class show with no preparation, Brendon has Melissa and Jason just follow his lead, and they go into a haphazard interpretive dance number while scat-singing about rice.
 * Phineas and Ferb do it at least Once an Episode. Taken Up to Eleven in Rollercoaster: The Musical, which features this in just about every other scene, and is naturally Lampshaded.
 * Rocko's Modern Life had a Musical Episode where everyone broke out in song and dance numbers. When Rocko questions it, Heffer remarks that they have rehersals, which Rocko has apparently been missing.
 * Family Guy does this a lot particularly the numbers "Shapoopie", "A Bag of Weed", and "Mr. Booze".
 * In Batman: The Brave And The Bold, the Music Meister's powers are only given as singing-based Mind Control, but Spontaneous Choreography and spontaneous wardrobe changes seem to fall under his Required Secondary Powers. In another episode Huntress, Catwoman and Black Canary are sneaking backstage at the biggest hoodlum hangout in Gotham when the curtain goes up. They pretend to be the entertainment and launch into a risque song about superheroes with spontaneous choreography and perfect unrehearsed harmony with both the house band and each other. The villians love it.
 * A few songs in My Little Pony Friendship Is Magic feature this, like "At the Gala" from "The Best Night Ever" and "Smile, Smile, Smile" from "A Friend in Deed".