Put it immediately after the unbelievable claim, as the reaction that closes the moment, then follow it with the Law and Order Dun Dun for a dramatic verdict before cutting to the next scene.
關於此聲音
This is a short French voice clip, just under five seconds long, of Julien Lepers exclaiming 'Mais c'est fou' in a rising, incredulous tone. It lands as amused disbelief, the sound of someone hearing something too absurd to believe and reacting out loud. The delivery makes it feel playful rather than angry, like a stunned laugh at an impossible claim.