The Mockingjay comes from Suzanne Collins's The Hunger Games, where the mockingjay bird and its distinctive whistle became a symbol of rebellion in the books and films. As the series grew into a major fandom, fans lifted the short four-note melody for ringtones, phone alerts and fan videos, with SMS versions made to fit the brief sound of a text notification. It has stayed popular because it is instantly recognisable, easy to place, and carries the feeling of a secret signal without needing any dialogue or explanation.