Try teaching year 7's to screenshot, they get scared when you tell em 'print screen' literally means 'take screenshot of the screen and use the printer' what idiots....doesn't anyone trust me? Well all in good reason I guess
I can't play pranks on my boss, would be dangerous, being a kitchen and all, so insults works just as well
to annoy teachers/bosses, throw the computer on the floor and say it crashed and a technician needs to see to it, I would do it the the dep. Head of sixth form...but he has been known to throw the odd chair in stress....