I kind of went through a similar experience a couple of years ago.
It started when I found a school locker lock stuck on a desk in my math class. I thought to myself, "I wonder if I could break it off of there?". The next day I came to school with a screwdriver and managed to pop off the back of the lock and completely take it apart. Success!
Being a nerdy kid who wanted to see how things worked, I of course played with all the parts and examined the lock. It was around this time that I made the discovery that all locker locks have a keyhole in the back. Further investigation revealed that administrators actually have a key that can fit all of the locks!
Being that nerdy kid I am, I set out to make my own using the tumbler from the lock I had just taken apart. 30 minutes with a file and an old house key later, I had a home made key ready for testing. I showed my friend the next day and we ran over to my locker to give it a test. *click* It opened right up. Then we tested it on his locker, and the same thing happened. This thing is pretty cool!
A couple months later me and a bunch of my friends all had these keys and used them to open our lockers and each others if we needed. We
never used them on anyone elses, because we knew that that was a sure way to get us in trouble. We were all honors kids afterall, so the thought of stealing hadn't even occured to us.
Some time the next year (sophmore year) it was leaked that a bunch of us had keys that could open all 2500 lockers in the school. The school administration obviously thought that we were stealing anything we could get our hands on (which we weren't) and called us to the office one by one. We explained that they were only used on our lockers and we would never dream of stealing. The school cop wasn't easily convinced, and he compared us to "common low-life killers" and promised to ruin our lifes if we didn't fess up to stealing stuff. Eventually they saw that we weren't crooks, and they confiscated the keys and let us off with 3 days of suspension (5 for me for being the "ring-leader").
Looking back it was a really stupid thing to do and I'm lucky that no real theifs got ahold of any of the keys. (I was a freshman, I didn't know any better!)
But somehow the school hasn't learned their lesson and they still have the same locker system. Someday a real crook is going to find out the same thing I did, and then they'll be in real trouble...