8. Bribery
How badly do you want to know what's inside your presents? Perhaps a trade could be arranged with somebody that you know has been told what your presents are. This would probably not work on a close relative, but would be more effective on a work colleague of your parents - no emotional attachment, no reason not to do business with you. The cost will depend on how desperate you are to get the desired information, or how many presents you want to find out. It is far more profitable to be the person being asked, which is why it is tactically sound to know as many people's presents as possible so you can trade information for your own search for answers. This method might help you, but be wary of the consequences. There is hardly anything sadder than bribing a person £10 to find out that a loved one has bought you a £5 gift voucher.