True story with a happy ending: I took a class called "Administration", it turned out to be just doing spreadsheets... so I just brought in / downloaded emulators and such all the time. I found a hidden folder on the network that was tucked away, but everyone had read / write access to. I put all the stuff in there.
A lot of pupils throughout the school knew about it, and it wasn't until two years after it started (by which point I had over 1.5GB of stuff on there) that it got noticed. And I don't know if they were just impressed or what, but all I got was a slight "Don't you do that again!" from my computing teacher.