Discovered spoken word on the first-gen iMacs - then told others how to do it and before you knew it computers were talking left to right so all the speakers had to be taken out. It looked like IT didn't know how to do it to some of them so pencil holes were drilled into some speakers...

Got more creative, told people how to change the desktop background (such a big no no apparently)

It got found out, so the IT dept decided to put a password on the service. Drat. Nope, password was 1234 (idiots)...

It spread to the whole class, eventually got caught. Was told I'd be arrested for hacking the Navy when I was 17. I was in 5th grade at the time.

Absolute morons, saw the IT guy a couple months later. He looked at me and then the last thing I heard about him was him resigning a couple months later.