I remember when I was around 15 someone stole some gameboy games from me, which weren't even mine (borrowed from another friend).
When I found out about the missing, I instantly had that particular "friend" in mind who was the only prime suspect. Sure I had no 100% prove it was him, but he came over the otherday and after that they were missing.
So I confronted him and made up that story, that few games that we recently played together suddenly were missing and that I had rented them from a shop, and if I can't find them back I would have to pay the full price to that shop and that it would financially completely ruined me.
Seemed that I really touched a weak nerve on him, because he suddenly offered to help me to find the games back, but that he first have to go home to do some stuff and come over to my house to help search the games later on.
When he came over, I said that he can go to my room while I would get me some juice from the fridge, when he went into the room, I spied him out what he's doing and I saw him crawling under my desk doing something there (lol). So I was letting him play his game.
When I entered the room, he was looking around at several places pretending to finding the games and eventually he's crawling back under that desk and yells with a big suprised voice that he just had found the games lying there behind the desk.
I didn't took any further action against him, but was innerly ubersatisfied that my plan of getting the games back came together with a full success.
OLOLOLOL!!!