One of the tutors at a course I was doing at the time, was known for one of those "I have been around, therefore I know everything" types. Anyway, we had all brought our personal PC's to the class one day, and he asked us to take the sides off our cases, so everyone else could have a look. Later on in the class, he was explaining to one guy on the "proper way" to remove a heatsink, grabs this guys case, gets a flatblade screwdriver, and proceeds to shove it into this guys case. All of a sudden, the tutor lets out a rather loud "F*@K" and stares in horror at a screwdriver that he had just shoved THROUGH this students motherboard. $330 later, he still can't live it down :)