Place this clip right after the reveal in a short edit, not under the build-up. Open with a WhatsApp message sound for the bad news arriving, follow with this clip for the reaction, then cut straight to the exit shot.
このサウンドについて
This is an eight-second clip of a single voice stretching the word run into one long, urgent Ruuuun that keeps going well past a normal warning. It feels funny and panicked at the same time, the sound of a joke emergency where the only sensible reaction is to turn around and get out fast.