Place it right after the reveal lands, with sudden suspense just before it, then follow it with oh my god wow for a second reaction, and add cartoon slip last if the scene turns into slapstick chaos.
About this sound
This four-second clip is a single high-pitched voice crying 'oh my god' in a stretched, squeaky burst that rises sharply and stays light rather than loud. It feels startled, silly and over-the-top, like a cartoon gasp at something unbelievable, and it lands as pure comic shock instead of real panic.