Place it at the exact frame the mistake becomes unavoidable, after a build-up and before the payoff shot. Pair it first with sudden suspense for the warning beat, then follow with a no no wait wait clip when someone tries to reverse it.
About this sound
A single voice blurts oh no, then keeps repeating no in a fast, rising string that runs for about 14 seconds without letting up. It lands as pure alarm that tips into comedy, the sound of watching a mistake unfold and being unable to stop it, argue with it or look away from it.