Megaphone feedback is a classic stock sound effect rather than a clip from a single film, show or viral video. The harsh squeal is created when sound from a loudspeaker is picked up again by a microphone and amplified in a loop, a common fault with PA systems, megaphones and stage speakers. Online, editors use the short, recognisable noise as shorthand for a botched announcement, an overconfident speaker or a moment descending into chaos. Its simplicity keeps it useful across pranks, skits and reaction edits, where one sharp burst says more than a long explanation.