Place it right after the failed promise or bad decision in your edit, then follow it with the Sad Violin for a mock-serious moment before the punchline. If the let-down was a clear mistake, open with the Wrong Answer Game Show sound first, then let this clip deliver the verdict.
O tym dźwięku
This is a short French voice line, just over two seconds long, in which a speaker tells Damien, plainly and without shouting, that he disappoints him a lot. The delivery is calm, flat and a little weary, which makes the rebuke feel sharper than a shout. It lands as a dry, teasing put-down, perfect for calling out a friend's let-down with a straight face.