How did you mess with school computers?

Put some VB script (I think) that opened and closed the CD-ROM 50 times inside a startup folder. Did it on all computers. Also put a batch file there that shuts down the computer one second after logging in on all teacher computers.

And last but not least, I created a phishing Facebook page, opened it on some browsers in school, rewrote the URL to a Facebook one (without pressing enter) and left it there, collected some passwords.

Edit: Also installed Ubuntu (dual booted) on the computer I usually used.

Edit2: Disabled the tracking software for a computer I used. Damn, it's all coming back to me! Good times.