During the course of the movie, show etc etc... the characters somehow end up being in a crowd with some nice music. Alice wants to dance, and so she does... then pulls Bob. When Bob was being drawn, he pulls Clair. And while doing so, Clair grabs Emely, and so on and so forth, until almost everyone is in the dance.
This is the Dance Line - wherein people who normally weren't dancing earlier dance because they are pulled in, and in doing so pulls another one from the crowd. Singing isn't required, but when it does, it may soon end up with a Crowd Song. Bonus points if Bob or the others cannot dance.
Related to Crowd Song. Usually a form of Happy Dance. Compare Dances and Balls; because your typical dance has people watching, talking, resting, or taking refreshments as well as dancing, it can occur at one, but it's rare.
- Rapunzel does this upon visiting the Kingdom in Tangled as part of her Falling-in-Love Montage.
- Near the end of Happy Feet, the main characters are trying to get all the penguins to dance, over the objections of the elder. They're not forced to dance, per se, but convinced to dance, causing a sort of domino effect.
- In Just Visiting, when Andre and the neighbor maid Amber visit a nightclub, they initiate one which promptly shows Hunter two-timing with another girl.
- The title character does this in "Cuban Pete" sequence in The Mask. He pulls a female police officer out of a crowd of cops and starts dancing with her, and soon everyone's dancing in a conga line.
- Jenna does this in the Thriller sequence in 13 Going on 30.
- In The Muppets, the first song in the movie entitled "I Have Everything That I Need" features this as Gary and Walter sing in their neighborhood.
- Although the 1996 Japanese "Shall We Dance" ended with an actual dance, it still drew in more and more characters who had not actually intended to dance.
- The 1971 film Protein synthesis: an epic on the cellular level, made for Stanford University, illustrates protein synthesis as a delightfully hippy-dippy line dance with balloons and Jabberwocky-inspired narration. View it here!
- Never On Sunday is set in Greece and sure enough, the theme song features one of those Greek dance lines with the inevitable bazouki accompaniment. note
- A very creepy one in Seeker's Mask by PC Hodgell. Most of the priest's college had been in one for days. Not all of the dancing priests are still alive...
- In How to Succeed in Business Without Really Trying (at least the 2011 revival with Daniel Radcliffe; other versions may have had different choreography), J. Pierpont Finch pulls executives from their herd to exemplify problems such as mediocrity and incorporates marshals them into a dance for "Brotherhood of Man."
- In the Avatar: The Last Airbender episode "The Headband", Aang is trying to teach some Fire Nation kids how to relax and have fun and does this at his secret dance party.
- In an episode of The Simpsons, Mr. Smithers is sent on vacation, and goes to a gay resort. He calls Mr. Burns to check up on him...and a conga line forms behind him at the payphone, which he proceeds to lead.
Mr. Smithers: Well, I've gotta go. There's a line forming behind me.