One Piece began as Eiichiro Oda's manga in 1997 and became a long running anime in 1999, known for hugely expressive reaction sounds. The gulp fits that style, using a familiar cartoon swallow to show fear, hunger or embarrassment in a single beat. Clips of these reactions were widely shared by anime fans in edits, reaction videos and soundboards, where short, recognisable cues travel fastest. It remains popular because the meaning is instant even without context, and the One Piece association gives it extra weight for fans of Luffy and the Straw Hat crew.