Place this near the reveal in a safari or zoo edit, after a tense build-up sound and before a bruh meme response from your characters. It works as the turning point, so let the next reaction sound carry the payoff while this one marks the shift.
About this sound
This is a brief whistling call attributed to a black rhinoceros, lasting just over a second, with a high, cartoon-style animal sound rather than a realistic roar. It feels silly and surprising, like a wild animal doing something completely dainty. The clip comes from the Goofy cartoon African Diary, released in 1945.