Scooby-Doo first appeared in Scooby-Doo, Where Are You!, the Hanna-Barbera cartoon that premiered in 1969 and followed a group of teenage mystery solvers and their talking Great Dane. The character's nervous, double-take reactions became one of the show's most imitated traits, long after the original series ended. Online, short clips of those reactions are reused as shorthand for sudden surprise, especially in memes and reaction edits where a quick turn says more than dialogue. That familiarity is why the sound still works across generations of viewers.