I wrote a program to repeatedly open and close the mechanical CD/DVD drive and put it in the startup folder.
Aside from the computer/s mentioned above, my school was an Apple school. I got around filters by ssh'ing into my homecomputer with XForwarding.
A friend of mine installed the Halo demo on the school computers.
In middle school our one class played this computer game that was similar to SimCity, but wasn't. I found out the save files could just be edited in plain text. So I cheated. I never was very good at SimCity.
Not messing with anything, but I was learning Python in HS and I went to python.com. At the time it was NOT about the programming language. And it wasn't blocked. That was a shock sitting in the school library.