Place it right after the on-screen question or request, as the entire reply in the edit. Follow it with a no no wait wait button when the scene needs a second, panicked backtrack, or leave it alone as the final beat before cutting away.
About this sound
A short Portuguese voice clip, about a second long, of a voice saying Não, porque nem sempre, meaning no, because not always. It feels dry, mildly deflating and quietly funny, like a plain excuse that shuts down an assumption without drama, argument or any raised voice at all.