I am a Singaporean. We live in flats. If you've never lived in flats[apartments] before, well, let me tell you, it can be quite noisy having neighbours all over around you—above you, below you, and on the sides of you. Ok, that is nothing peculiar, but what I'm about to tell you is.
In early mornings, around 2 or 3 am, I hear the annoying sound of bouncing marbles above my apartment. That, to me, is strange. What parents would allow their kids to play marbles at that hour? What is stranger is that I'm not the only one who has experienced this. My friends have reported to have heard the bouncing marbles too. So, what is it then? Why do so many people experience this phenomenon? Is there an explanation? I'm perplexed.