I once had a VP of IT here who received one of our company's first color graphics terminals on the IBM mainframe. He had his boss in his office and was going to demonstrate his new toy for him.
But the screen was blank. So, of course, he called me directly (I was supervisor of network ops in those days). I walked into his office, said hello to them both, then reached over and turned on the power switch.
Executed a smart about face and left the office.
The Sr VP saw me in the elevator and asked me how I kept a straight face earlier. My reply -- never bite the hand that feeds you. :-)