Place it after the slow realisation in a clip, then follow it with a shocked sound for the payoff, or lead into it with a goofy yell when the joke needs a bigger build-up before the reaction lands.
Über diesen Sound
This clip is a single drawn-out vocal sound lasting just over three seconds, with one voice stretching the word douuu into a long, wobbly note. It feels silly and deliberately overdone, like someone milking a reaction for comic effect rather than saying anything at all. The stretched delivery makes it land as a playful tease, a mock-dramatic groan, or a light-hearted way to drag a moment out.