Encore comes from the French word for again, and shouting it at the end of a concert became a long standing tradition in live music and theatre. An audience that chants it together is asking the performer to return for an extra song or a final bow instead of letting the night end. As short form video grew, the chant was lifted from live recordings and reused as a reaction clip online, where a few seconds of unified demanding now instantly signals praise, excitement, and a wish for more of whatever just happened.