The cuckoo call comes from the traditional mechanical cuckoo clock, where a small carved bird emerges on the hour and imitates the bird's two-note song. That instantly recognisable sound became a shorthand for time, waiting and gentle silliness in cartoons, children's programmes and comedy, long before it spread as a short clip online. Creators now reuse the brief call on its own, divorced from any real clock, because listeners understand it immediately without explanation, and its short length makes it easy to drop into edits, memes and reaction videos.