Mr Sean Cheong knows that his elder son, Lucas, 14, spends money on mobile games.
Lucas used to charge about $100 to Mr Cheong's credit card, which is tagged to his iTunes account.
This month, Lucas charged $4,300 to the card, giving his father "the blardy shock of his life".
The boy sheepishly admitted to spending the money on extra moves and boosts in Candy Crush Saga, a mobile phone app that has taken the world by storm.
According to Forbes.com, it attracts a daily 9.7 million Facebook players and is the top grossing Apple app.
While Mr Cheong is reeling from the sum, another parent says she'd rather pay for her child to play rather than risk him mixing around with bad company.
Counsellors and psychiatrists warn against allowing children to indulge in long hours of play, saying that it could make them indifferent to the real world.