Okay story time:

I am a student at my high school where this year they pretty much fired the local IT guy and put 16 students in and two teachers to supervise the work that we do. Now we had access to the entire DISTRICT mainframe and had basically full administrative rights to just about everything. One of the kids in our IT class decided that one day he was done with a students crap so he remotely shutdown his computer multiple times. Well our supervisor found out and revoked everyone of any rights to anything. If anyone so much as lifted a finger we had to tell them exactly what we were doing. They said they were going to change all the passwords and lock the kid out of his student account on the computers. Weeks go by as we have to constantly ask for passwords to be typed in and have to get authorization to reset and manage network servers. Now remember that kid? He came back after being gone, he tried to log in to his normal account to do some work. To no avail the account has been locked, so he goes over to sys-admin and asks to get some files. Admin obliges and let's him get on. Admin unlocks his account and Immediately the kid goes in and tries admin with CMD. The passwords all work. I'm sitting there In shock as this kid shuts down EVERY COMPUTER IN THE ENTIRE DISTRICT. ONE BY ONE YOU HEAR THE COMPUTERS SHUTTING DOWN, KIDS AND TEACHERS ALIKE GROANING BECAUSE THEY DIDNT SAVE. We get calls a half hour later saying that the network has been comprised and that they have no idea who did it because all the logon servers were down. He got away Scott free. Everyone thought that it was an unplanned stress test somehow and he still randomly shuts down computers in the library and labs for no good reason other than the pure enjoyment that is seeing people in agony.

TL;DR: I'm admin. He's admin. Servers and one computer goes down because of him. He gets suspended. Comes back. Shuts down entire network because nobody changed password.