Put it at the end of a reveal sequence, after the opening clip and before the closing reaction, so the moment builds instead of starting at full force. Follow it with Brother Eww for a second wave, or lead into it with Oh My God Wow when the reveal needs a slower build.
About this sound
French YouTuber Antoine Daniel opens with a brief line in French, then lets out a long, rising WOOAAAA scream lasting about four seconds. The yell feels playful and absurd rather than truly frightened, turning mock disgust into a joke. It comes from his reaction video to the notorious shock clip 2 Girls 1 Cup, where the scream served as the punchline.