The turbo flutter, often written online as stututu, comes from real turbocharged cars, where compressor surge creates a rapid flutter when boost pressure has nowhere to go after the throttle closes. Car enthusiasts have long recognised the noise as a sign of a tuned or heavily boosted setup, and short clips of it spread through car forums, social video and gaming edits as shorthand for speed. It remains popular because it is instantly recognisable, needs no explanation, and adds a mechanical, high-performance feel to even a brief clip.