This thread reminded me of something I did some time ago that I'm not all that proud of, so I'll put it up here for all of you to see. Probably 15 years ago now, my girlfriend at the time had met a couple, and they became our friends and would come over, hang out sometimes, etc. I wasn't all that fond of them, but my girlfriend liked the female of the pair, and seemed to be good friends.
One morning I went out out my car, and the window was broken. My gf hadn't removed the stereo faceplate, and well, the stereo was gone, which was a shame because I really liked that stereo. Fast forward a couple of weeks and I went over the the couple's house to pick up my girlfriend, and while I'm there, I spot a pawn shop receipt on a hutch in their dining room, it's a receipt for a car stereo - the same model that was stolen from my car. I know the two cars my "friends" have, and they don't have a stereo anything like this. It isn't too hard to figure out what happened. I wait to do anything until I talk to my gf, and she implores me to just let it go and break off contact. OK, fine, although I'm not happy about it.
So, I don't hear from them for a few weeks, and there's a knock on my door one day, and it's the "better half" of the wonderful couple. She has a box in her arms, and says she "ordered" some computer parts and wants to know if I can build the computer, since I'm good with that kind of stuff. Ignoring the obvious question of why people who know nothing about computers order computer parts, I decide to do a little investigation. I tell her to give me some time (a few days) to put it together. Now, the packing slip is inside the box, (it was from Newegg if I recall) and it doesn't have the address, but it has a name and the component model numbers. Looking around, I ascertain there's some nice parts in this box, better components than I have by far. So, I call the police, which is stupid for this type of thing, as I basically get the runaround for trying to do the right thing, and I'm told to do whatever I please with these parts.
The next day I call the girl, tell her she has just about everything she needs for the computer build, except the case, and I give her some options for one. She brings me a case a week later. I wipe my computer, remove the components, put it into her case and give it to them. They're so happy they pay me 20 bucks for putting it together. I'm happy because I have a much better computer. I got some revenge, and it's my hope that the actual Newegg customer got their parts. If I could have found out who it was I just would have given them the components, ah well.