Toe-Tapping Melody

Someone in a fictional work starts playing a tune. In most musicals, people either join in or serve as the background characters. Then you have a song that inspires people to join in, listen, or even clap. You can feel the joy.

Toe-Tapping Melody is one that inspires a nearby audience or individual to follow along, either by joining in to sing, clap, or acknowledge that it's a catchy melody. It may overlap with Ear Worm if the individual cannot get the song out of their hand. Participation or commentary is key to this trope.

How is this different from a Crowd Song or Audience Participation? Because in-universe, the crowd song or participation may not be spontaneous. Or it can be as little as someone singing along.

Note: The Tv Tropes version of this is called Actually Quite Catchy. I don't like this one because it equates the trope with "Actually Pretty Funny". Happy to brainstorm another title as well.

Advertising

 * [In an award-winning anti-smoking ad], several teens go to confront tobacco executives about the hazards of nicotine. The business executive starts a musical number to "Just Focus on the Positive"; the teens can't help but join in with the number, and drag in the various background extras, including paramedics, nurses, and hospital patients. Yes, that includes the dead ones..

Anime and Manga

 * Played to horrifying effect in a Junji Ito one-shot where a musician plays a screaming melody asking someone to leave her alone. Anyone who hears it can't get it out of their head. Some may hum along. A doctor reveals that the melody is a manifestation of the musician's stalker ex-boyfriend, that died by suicide in front of the musician.
 * The youma in a Sailor Moon episode invoked this by using a soundwave that compels anyone who hears it to want to perform.

Film

 * Subverted hilariously during Hoodwinked. When the Wolf, Granny, Twitchy and the Woodcutter witness, Granny comments, "This is terrible!" Wolf agrees because the rhythm and dancing were way off for the musical number.
 * Happens during Lilo and Stitch. During the fight with Stitch in the Pelekai household, Jumbaa turns the record-player on by accident. He starts swaying to the rhythm of "Hound Dog," giving Lilo and Stitch an opportunity to convene in the kitchen.
 * Tangled shows a contrast of this during "I've Got A Dream"; as Flynn watches with bemusement while Rapunzel defuses the bar patrons. She asks them to sing about their dreams, and dances with them. While Flynn needs to be threatened at knifepoint to sing as well, several rats are bobbing along to the music, as a confused Pascal observes.

Literature

 * In the Discworld novel Soul Music, that this happens is a plot point. Music with Rocks In turns Imp into Buddy, a spoiled diva musician that forgets his harp background when he plays a magical guitar from a mysterious shop. Susan notes that the music itself kept him alive past when his hourglass was supposed to shatter..

Live-Action TV

 * Brooklyn Nine-Nine has a Cold Open where Jake has a witness evaluate a criminal lineup. She didn't see the criminal, but heard him singing "I Want It That Way" while hiding from him. Jake has each of the suspects sing a line from the song, but they all turn out to be great singers. He gets into it, shouting, "TELL ME WHY!" and getting excited when they all join in harmony..
 * Buffy the Vampire Slayer has an episode where Giles requests a night off from watching the Scoobies for adult time. He asks them not to bother him, bar any threatening emergency. Sure enough, an emergency happens so the Scoobies go and find him playing guitar at a cafe. While Xander is horrified, and Buffy is later after she hears about it, Willow smiles and says she remembers why she had a crush on him when he was the school librarian.
 * Scrubs
 * Turk sings "I'm gonna cut you open" when he learns he's been assigned to do J.D.'s appendectomy. He enters the room dancing, and Carla joins in with him. Naturally, this doesn't ease J.D.'s fears about his best friend being a goof about a life-threatening surgery.
 * Ted's a capella group practices at the hospital from time to time, going from theme song to pop music covers. While J.D. tries to avoid them on the night shift, Carla enjoys seeing them and dances along. A season 7 episode has Ted woo a woman named Stephanie Gooch by inviting her to jam on ukelele with his group, and they do a beautiful rendition of "Carry On, My Wayward Son". J.D. and the Janitor, who have called truce to help Ted talk to Gooch, stop to admire the group jam.
 * "My Way Home" has Dr. Cox, as part of a prank on J.D. involving the new intern Keith, has Keith call him to the hospital on one of his days off while Laverne's church choir sings "Payback is a bitch!" Keith starts bobbing along to the song, until J.D. levels a Death Glare at him.
 * "My Musical" reveals that all the song and dance numbers that Ms. Miller was seeing was

Music

 * Amanda Palmer encourages this from her audience. Many YouTube videos show her cheering on the audience to sing along if they know the words, and even if they don't. When they memorized her "New Zealand" song from YouTube, she apologized to them for changing the lyrics over a year.

New Media

 * The Fine Bros. Entertainment "Try Not To Sing Along" challenge features this for its participants. FBE employees, old and young, need to listen to popular songs and are not allowed to sing along, hum, move their lips, clap, or even so much as tap in rhythm to the music. One deleted video showed that Spongebob Squarepants is super-catchy and hard to resist.

Newspaper Comics

 * Mentioned in a one-off gag in Pearls Before Swine. Zebra says that his herd on the savannah has been using musical alarm bells for warnings about predators. When they go off, the herd sings along.

Puppet Shows

 * The Muppet Show
 * When Harry Belafonte performed "Turn The World Around," the entire Muppet show cast and crew joins him onstage for the last round of verses. Kermit lampshades that they don't want this perfect moment to end. Statler and Waldorf, who normally snark about how terrible the show is, also sing along!
 * Sesame Street
 * If Luis brings out his guitar, expect any nearby Sesame Street cast member to either listen to his song or join in on the tune. One sweet episode has Rosita becoming so inspired by his music that she asks for guitar lessons.
 * A musical guest will often perform and attract everyone's attention on Sesame Street. Highlights include Stevie Wonder, Denyse Graves, Little Richard, and Queen Latifah.

Theatre

 * Hatchetfield has this happen a few times in its various shows:
 * The Guy Who Didn't Like Musicals
 * Beanie's manager Zoey makes her employees do a new tip song. Emma is not into it, having to sing and dance for fifty cents, but doesn't want to get fired. While she's unenthusiastic, the coffeeshop patrons sans a very terrified and confused Paul enjoy the music. That is, until the patrons take a sip of their fresh coffee, choke, and collapse to the ground as the music becomes menacing when Emma threatens to quit. Turns out the singing zombies got to Nora and Zoey, and they poisoned the coffee with "blue shit" that turns everyone who drank it into a singing zombie.
 * Professor Hidgens plays his demo songs of Workin' Boys to a . While Emma is practically crying with frustration because, Ted bobs along and asks Professor Hidgens to hit them with another song.
 * "Honey Queen" has Linda and Gerald Monroe use a few hundred dollars and the Homeless Guy to get Zoey to belt at her coffeeshop job, by stuffing her "Tip For A Song" jar. Apparently Zoey fires up the whole coffeeshop in her attempts to impress who she thinks is a Broadway producer. Only problem is she blows out her voice and can only croak the next day, just as the talent show is starting.

Web Comics

 * The Check Please webcomic often showcases Bitty's love for Beyonce as a Running Gag. His roommates often hear him singing and dancing along to Beyonce in the shower. Insulting Beyonce is a good way to get on Bitty's bad side.

Western Animation

 * In the Avatar: The Last Airbender episode "The Cave of Two Lovers," several wandering nomads treat the Gaang to Sacred Hospitality as they encounter each other, braiding Katara's hair and adorning Aang with flowers. They also sing about a Secret Tunnel nearby that they plan to navigate. Aang and Katara get into the song and bob along, while Sokka is frustrated and wants to move on with their journey. Quite ironically, he learns that the nomads' music leads to the safest way to navigate the tunnels: badger-moles use earthbending to change the tunnels and singing to them convinces them to lead a path outward.
 * Comes up in Justice League Unlimited in the episode "This Little Piggy". Circe turns Wonder Woman into a pig out of spite; while the League goes to find Wonder-Piggy, Batman and Zatanna confront Circe. They convince her to give them an audience when Zatanna smashes her with a piano. For Circe to change Diana back, Batman has to bare his soul in front of an audience, singing "Am I Blue?" to Circe's nightclub patreons. Zatanna admits he has a lovely voice, and Circe reverses the spell just as Wonder-Piggy is about to end up sliced in a slaughterhouse. Diana thanks Batman for saving her; when he claims to not know what she's talking about, Diana walks off humming "Am I Blue?" cheerfully. Batman can't help but smirk.
 * Over the Garden Wall has a moment of this save the main characters. They hopped on a frog ferry without paying the fee, because Greg tossed the pennies away impulsively, so they have to disguise themselves as band members to hide from security. When Greg and Wirt accidentally knock out the bassoon player, Greg encourages Wirt to play. Beatrice the bluebird does as well, because she suddenly doesn't want them to go see Adelaide. Wirt picks up the bassoon and plays...and Greg's new frog suddenly belts a beautiful melody. The frogs sing along, and they allow the humans to stay on the boat as long as Wirt keeps playing. They even offer Greg's frog a musical contract, but he chooses to stay with the trio.