Setting aside Kirk forgetting the concept of object permanence, WHAT was Spock doing?
He... He was actually whistling in this scene (exactly like that trope) and I had to blast the speakers to full volume and stick my ear near to hear but it is there... and... I can't handle the implications...
That at some point in his life, he probably saw Earth shows or cartoons where a character would start whistling like this and he asked someone, likely Amanda, what it was for. And Amanda probably explained that it's commonly done (in these shows) to seem less suspicious and that he honestly believed that to be true. Believed it enough to try it himself.
Maybe he even tried it in Vulcan and the Vulcans were baffled enough to look away and pretend to ignore him, reinforcing his thinking that the whistling works. 🤣