Ghostly Bouncing Marbles

My name is Donald, and like most Singaporeans, I live in a flat. If you've never lived in flats (apartments), well let me tell you, it can be very 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 has 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.

I haven't a clue to whether this would be considered paranormal, but I thought to share my story nevertheless.

Peace.