The origin of this short clip is not documented, so it is best understood as an online reaction sound rather than a line from a known film or show. Clips of this kind, a single hummed response with no words, travel easily because they need no translation and fit into short-form edits. Creators reuse the 'ng ng' hum as a way to signal agreement, teasing or a knowing look, and its brevity makes it easy to layer over gameplay, pets, conversations and moments without drowning out the main audio. That flexibility is why it keeps appearing in meme edits.