i have admin privledges on my school computer rule

wipe it all and install arch linux

If they're Windows PCs, edit the registry so that the Recycle Bin will be called the "Shit Can". lol.

spin up a linux VM and man-in-the-middle the network, replace all images requested from the internet to be replaced with images of nick cage.

set it on as cron-job to activate/deactivate randomly, only for a few seconds at a time once or twice a week.

I once managed to get creds for one of my teachers accounts which would give me the ability to see what anyone was doing at any time and kick and restrict student accounts.

Was so scared of using it i never did though

I once wrote a batch file and deployed it to a group of VM’s in my high school that would make disc drives open and close repeatedly.

Resulted in the high schools small NOC having several servers opening and closing their drives over and over much to the confusion of the IT guy haha

Try setting up a bat file that starts at launch that will at some interval play the audio track of Shrek 2 through some form of media player(preferably one that can be opened in the tray to delay people figuring out what is happening).

Learn how to use that without being detected. So don't troll. You have power right now. Don't play cat and mouse with what has been accidently gifted to you.

There's probably some macro utility you could run as admin which could send keystrokes. Maybe every 180 minutes have it pick from a list of human body parts and type it.

Change the desktop to Shrek or any other meme.

In middle school I would send popup notifications to classmates.