It's about those gargantuan marbles! I don't even know how you call them in English we just call them Supermegaberenbonken!
The song is in Dutch but you may interprete it as jibberish.

It's the result of a 'Djingle Djengle' session where me and a friend receive a bunch of tweets with random subjects. We pick one and create a song about it in one night.
For this song someone tweeted 'Marbles'.