The chant comes from Pixar's Finding Nemo, released in 2003, where young reef fish sing it while daring Nemo to swim out toward a boat, turning a moment of peer pressure into a playful song. The line stuck because it is short, rhythmic and easy to imitate, and it later spread online as a reaction sound for shark videos, beach trips and moments when someone is about to do something brave or foolish. Its simple call-and-response feel keeps it useful for quick edits, since viewers recognise the teasing tone even without seeing the film.