How scared should I be?

Okay, so this weekend I babysat my friends kids, so that she and her hubby could have a well deserved night out on the town. Their lovely little girl was in bed fast asleep when I got there, so there was not much work for me to do there. The little boy (who is just turned 9) was still up and we got to spend a quality 2 hours together playing top trumps and most of the time he was a grand little fella. However, he was allowed a couple of treats, so he had them and then tried to persuade me to let him have more sweeties. This little guy is a ball of energy all the time, so I decided it would be best not to let him have any extra as he would be bouncing off the walls by the time it came to go to bed. So, we’re sitting there happily playing top trumps with the TV on in the background and on comes some advert with a screaming baby in it. His voice drops and he looks up at me and says “I wish I could make myself roar crying like that baby, so I could make you all guilty and give me more sweets”. I was flabbergasted. I am fully aware that the kiddies a lot of time can pull at your heartstrings, etc, but really thought that they didn’t KNOW they were being manipulative and were just doing what instinct told them to!! Are all youngsters this consciously aware of manipulation methods, or does this guy just have special skills?