Place it at the end of a theory breakdown in your edit, right after the big reveal lands and the speaker finishes. Follow it with a cut to the listener's reaction shot, then a brief comedic sting. Precede it with a record scratch effect earlier in the sequence so this closing line resolves the whole bit cleanly.
About this sound
A short two-second voice clip of someone speaking in French, saying 'Oui, je connais cette théorie' — yes, I know this theory. It lands with a calm, knowing confidence that feels a little smug and amused, like the speaker was waiting for the explanation to catch up to what he already understood.