There are many ways that one can make any IT staff member upset, but I present to you some of the sure to displease methods of getting them upset with you.

Install plenty of software
If you have enough rights on your computer, install any software you like. Then, when your machine grinds to a halt, make sure you don't tell the IT staff about any software you loaded. Let them assume you have a standard issue machine and spend countless hours trying to fix your problem before realizing what you've done.

Open any and all email
Open an email from someone you don't know. If there's an attachment on the email, open it and see what it is. If it's an executable, make sure you run it to see what it does. If nothing happens, disable that pesky antivirus software and try again, and only then check with a coworker to see what it might actually be. At this point, you should be getting responses from people who are getting email from you, which you didn't send, and a member of the IT staff should be storming your way. Now might be a good idea to go hide.

Play "musical cables"
If you see a bunch of wires in the development server room, why not play with them? Go ahead, there's enough that messing around with one or two shouldn't cause too many problems. Unplug them, and switch them around. If you're lucky, they won't be labeled and you'll have fun, meanwhile the servers around you begin to go down because they cannot access the network. You might also be greeted by flashing lights, but to you, that means you're doing something right.

File hide and seek
Delete some files off of a server. They aren't your files, so they must not matter, right? Better yet, uninstall some things that you think the server doesn't need. "SQL Server, why do we need that?" you think, and a few clicks later and it's gone. Granted, this is a test server that you are allowed to be messing with, but when your coworkers realize the server is gone and call IT, then guess who IT is going to ask about the SQL Server?

Configuration Files are for your enjoyment
You've seen them before. Files ending in .INI or .CFG, and you've even heard about something called Regedit. Play with these, make sure you make some changes that you think will make a difference in your system, and then reboot your computer. When things don't go as planned, call IT and let them know that the machine they have provided you is a piece of garbage and you want another one. For an added bonus, make sure you try some of the registry tweaks you find on the internet on your machine.