Place it at the reveal point of a fail edit, after a no no wait wait button sets up the warning, then follow it with a wrong answer game show sound to close the sequence without another reaction line competing for the moment.
À propos de ce son
This clip is a brief spoken reaction built around the clipped phrase 'shouldn't've been,' delivered as a regretful aside rather than a full sentence. It lands funny and awkward at once, like catching a bad decision a second too late, and that unfinished feel makes the regret hang in the air for the listener.