1> Put a sign outside the school over summer vacation that says "Coming Soon: HCA Hospital
2> Post the school phone numbers on here so we can prank call them
3> Find one of those emails in your inbox or junk folder telling you that you have an "e-card" from some random person or something to that effect and write down the URL on a piece of paper (the real URL it links to, not the Hallmark or whatever URL). Go to that URL from a school computer. This will result in the school's computer spewing out spam or participating in DDoS attacks.
4> Trick the cafeteria people into pulling the Ansul, or trick the cheerleading coach into pulling the fire alarm.
5> If there's payphones, redbox some calls to foreign countries.
6> Also, make some prank calls from those payphones
7> If there's payphones, share the numbers from them with us so we can play with them.
8> Try and change the desktop background on all the computers to the PLA bell logo with the word "Cactus?" under it
9> Find the NID for the school's phone line. There's plenty of fun things you can do with that.
10> If there's anything at the school that involves a credit card machine, tinker with the credit card machine. Maybe report a debit card as lost and try and use it there so that the cashier has to keep the card and call the operator.
11> If you can get on YouTube, rickroll everybody in the library.
12> Tell someone you don't like how fun it is to vandalize Wikipedia. If they take the bait, report them to the computer authority for abusing the network.
13> Sign the principal (or some teacher you don't like) up for every possible magazine using the "bill me" option. Use the school address for this.