Castanets have been used for centuries in Spanish folk music and flamenco, where dancers click the paired wooden shells to mark rhythm, and the sound has long been shorthand on screen for Spain, celebration and theatrical dance. Online, short castanet clips circulate as sound effects for memes, reaction videos and edits rather than as a quote from a specific show, which fits this very brief recording. Creators reuse it because it is instantly recognisable, culturally evocative and easy to drop into a timeline without needing a full music track.