The sound comes from VTech electronic learning toys for babies and toddlers, where it works as built-in positive reinforcement. Press the correct shape, letter or button and the toy responds with this enthusiastic yaaaaay to encourage play and learning. Clips of the toys were shared on social media and soundboards, and creators began lifting the reward sound for unrelated videos. Its appeal is the pure, unconditional praise, which works both sincerely for children's content and ironically when adults celebrate very small successes.