Place this clip right after the on-screen yes in your edit, then follow it with the no no wait wait button when the person tries to back out, or lead into it with the sudden suspense sound button before the unwanted task is revealed.
About this sound
A short Portuguese voice clip, about two seconds long, of a man insisting he is not being forced to do anything and is acting of his own free will. The delivery makes the denial sound completely unconvincing, which gives it an awkward, funny feeling — like someone reading a statement while clearly doing the opposite of what they want.