SML began as SuperMarioLogan, a YouTube comedy series by Logan Thirtyacre that uses puppets and plush toys for parody stories. Bowser Junior, later shortened to Junior, became one of its main child characters, known for a whiny voice, selfish schemes and loud overreactions. Short clips of his screams were lifted by fans and shared on soundboards and in fan edits, where the yell works on its own without the original scene. It stays popular because the reaction is instantly readable in any context.