In an edit, put it at the reveal beat, after Sudden Suspense and just before Kids Cheering, so the reaction sits between the build-up and the celebration. For a different cut, follow it with Nelson's Ha-Ha! instead, letting the laugh answer the surprise.
Über diesen Sound
The Whoa-Hoo clip is a vocal exclamation lasting just under seven seconds, centered on a human voice delivering the sound as one expressive utterance. It feels playful and delighted, with a cheerful sense of amazement at something unexpectedly good, and it leaves the listener smiling rather than startled.