The sound comes from JoJo's Bizarre Adventure: Stardust Crusaders, where Noriaki Kakyoin rolls a cherry around his mouth and repeats rero rero while explaining his Stand to Jotaro. The odd, rhythmic delivery turned a quiet character moment into a widely quoted anime joke, clipped and remixed across YouTube, TikTok and meme edits. Fans still use it because it captures Kakyoin's playful, unbothered personality in just a few syllables, making it an easy shorthand for teasing someone without saying a word.