A Real Doozie that just sprang to mind.
I was working for an engineering company who changed their CAD provision from an ancient PDP11 based system to Sun Sparcstations.
The cheif electrical engineer got really annoyed when we wouldn't give him the super user password to his workstation (on the grounds it was dangerous, insecure and he didn't need it to do his job). He kicked up one hell of a fuss and eventually the order came down from on high to give him the password. We did but warned him that he was now responsible for his machine and we wouldn't support it unless a senior manager formally requested it.
Less than a week later we got a formal request from the site manager.
Having got full control of his workstation this guy decided to clear out any garbage files on his machine and found the /dev directory which he proceeded to completely empty!
Strangely enough, after that his machine wouldn't boot up.
We didn't gloat.... much