When I was a kid my brother and I considered Christmas a "failure" if we hadn't found everything by Christmas morning. They started getting smart and wrapping things before they hid them, but we got smarter and figured out how to un-wrap them and re-do them without being detected.

One year my mom lost one of my presents and had to ask us if we knew where it was. My dilemma was do I a) tell her that I know where it is and admit we had been snooping or b) not tell her and not get my Suntan Tuesday Taylor doll (that I really, really wanted). Greed won out - I told her where it was. They did eventually get better - they started hiding things in the trunk of the car, or leaving it at grandma's house and not bringing it home until the day before.