Place it right after the visual reveal in your edit, then follow it with a bruh reaction for the denial beat and an emotional damage hit if the joke escalates. Keep it as a single isolated insert between reaction sounds rather than stacking it under dialogue.
Über diesen Sound
This is a very short voice clip, under half a second, of a single spoken word: Marihuana. There is no music or extra effect, just that one word delivered on its own. It feels blunt and funny in a deadpan way, like a label dropped into a conversation at exactly the wrong moment for comic effect.