Well... back in our day, not long ago. Our IT class found out the administrator password rather amusing how we did it hahaha. We did it twice actually. The first time the whole school was using it LOL.
Towards the end of our HSC, we just decided to wait it out and not go for a 3rd attempt("you won't receive your hsc!"). I actually remember submitting a ticket to gain access to a site: "youtube.com" My claim was: "It's an educational tool" LOL
Also, the 2nd time we got it, some kids installed Quake 3 on it or Quake 2. Don't exactly know, but we played that in IT class when teacher was out (which was majority of time hahaha)
Another thing 2 years before that, I found the Mblaster virus and put it in the shared server (everyone had access to it, for specific classes)
That thing got spreaded around so much on older computers. The IT head teacher chose a group of volunteers to fix it, funny enough... it was the ones that put it on hahhaha.