Place it right after the reveal in an edit, following Sudden Suspense to build the moment, then follow it with Oh My God Wow to stretch the reaction before cutting to the next scene.
Über diesen Sound
This is a short, roughly three-second vocal reaction built around a single surprised 'oho', delivered with a light, rising inflection that sounds caught off guard. It feels playful and a little cheeky, like someone has just spotted something unexpected and cannot help reacting out loud. The clip comes from The Last of Us.