School System Security Solving

Good old solid /computers/ - more thoughtful than /g/, faster than /tech/.
I need to call on your collective help for one big thing.
First, some background information -
I have a Mac and a PC, PC runs Linux, but has a small HD, I tend to work off of Live CDs quite often, I don't know why, force of habit I guess. I can work bash pretty well, but I wouldn't call my knowledge of networks extensive.
I'm 18 thus at my last year at a shitty school. It's a seriously shitty, repressive school where the teachers don't give a fuck and I get comments from the IT staff such as "LINUX SUPPORTS PIRACY THUS SUPORTS TERRORISM, YOU CANNOT TALK ABOUT IT". So basically, on the final day, most students piss off the school by throwing eggs/releasing chickens in school etc.
I wanna be at a computer having more fun.
I know they don't password BIOS, and have booted from various LiveCD's, impressed friends etc.
Basically, I need advice, if I'm running nUbuntu or some security minded distro, what tools can/should I use to cause some mayhem? I thought listening with dSniff or ethereal to find passwords or something...
Anything from general advice to links to guides would be appreciated.
Be nice.

Need PROTIPs for screwing up the school? Messing with computers is boring.

1. Obtain some Surströmming (Swedish speciality, http://en.wikipedia.org/wiki/Surströmming).
2. Open can.
3. Put in unused locker.
4. Lock locker.
5. ????
6. Profit.

I wanna be at a computer having more fun.

Hacking a computer is more fun than throwing eggs with your friends?

I recommend you get out more.

install keyloggers

Try setting up a headless DHCP server somewhere. It'll provide hours of fun for tech support.

Also, changing the IP address of a machine to that of the gateway might be worth trying.

Poison the network with ettercap

do this:

ettercap -T -q -M arp // //

then PROFIT! Collect passwords then hack deeper and deeper into their network, then get into the schools webpage BWHAHAhahHAhAHa

HACK THE GIBSON