Kids understand a lot, but they don't understand everything!
Our two older boys are very keen on Club Penguin, but so far mean parents are forcing them to make do with free accounts. They know full well that there are things that they can only do if they pay for membership. Mr 6 was explaining for Mr 4 how much it cost to become a member and he decided that he would pay himself using coins from his moneybox. So he then posted a number of coins into the memory card reader of the laptop in an attempt to pay for membership. It would seem that they understand more about how the virtual world of computing works than the physical world!
Fortunately, the laptop did not seem too upset. Once the coins were removed, it rebooted and all seems well (so far at least).