HERSHEY's'

Bouncing MarblesI am a Singaporean. We live in flats. If you've never lived in flats (apartments), well let me tell you, it's quite noisy at times. Having neighbours all over the place. On top of you, below you and both sides of you. Ok, that is nothing peculiar but what I'm about to tell you is.
In the early mornings, around 2 or 3 am, I hear bouncing marbles above my apartment. That, to me, is strange. Which parents would allow their kids to play marbles at that hour? What is stranger is I'm not the only one who had experienced this. My friends have reported to hear the bouncing marbles too. So, what is this then? Is there some other explanation? I'm still perplexed.