Place it right after the offending line in an edit, so it closes that moment before the scene moves on. Open with the Wrong Answer Game Show buzzer for a bad take, follow with this shutdown, then let the Nelson Ha Ha laugh finish the sequence.
About this sound
This is a very short French voice clip, lasting just over two seconds, in which a speaker snaps out the phrase 'mais tu ferme ta gueule ok' in a blunt, dismissive tone. It feels sharply funny and satisfying, like being cut off mid-sentence by someone who has completely run out of patience. The abruptness makes the insult land as a joke rather than a real argument.