Actually there is the trick I did with one kid who just crossed the line:
It was about 3:30am, I had a final exam at 8 in the morning & really wanted to get to bed. Anyways I was just starting to get ready to go to bed & someone knocked on my door..."Help, I can't get any programs to work on my comptuer & I have to write a paper for tomarrow." Anyways, I figured this would take about 5min to fix (the way he described the problem I was pretty sure I just needed to fix his user permissions), so I decided I'd do it for him.
Anyways, I get down to his room & had him log on as "administrator". I then first removed his firewally program from his startup folder (as he had troubles accessing the internet he said as well). After doing this ICQ popped up (he was sitting in the chair at the time), and he proceded to talk to someone on ICQ, for all of 30 minutes, telling me that he's almost done all along. At the end of the 30 minutes, I finally got control of the comptuer long enough to 'fix' his other problem, I made "EVERYONE" an administrator on his comptuer, and left.
I then went back to my room....loaded up "\\dave\c$", and proceded to change his start menu button to read "I'm a Stuipd Idiot", along with numerous other changes (such as denying him access to his mp3 folder, and others). Revenge is sweet. From what I hear, he actually had to send his comptuer back to dell to get it fixed....,how fun.