Place it at the end of a failed attempt, after the action has already gone wrong. Put Dun Dun Dun before it, or use SpongeBob Fail first and let this clip close the sequence as the final reaction.
このサウンドについて
Downer is a short sound effect lasting about 2.7 seconds, built around a single falling pitch. It gives a sinking, disappointed feeling, the sound of enthusiasm draining out of a moment and leaving it quieter than before. It works best as a small, dry reaction to a disappointment.