Try plugging in a molex connector upside down... It smells like money
Try installing a new bigger better video card and neglect the power supply capacity.. Poof goes the psu (system survived somehow).
Try dropping the metal clad flashlight into a powered up motherboard.
Try to clean the pins of a socket 775 cpu socket
Try installing a new mobo into an existing machine and have no back up of the drives
My favorite error message is "Keyboard error or keyboard not present, press any key to continue"
and lastly a few allegedly 'true' service calls.
"Customer - I was working on the pc when the screen suddenly went black !"
"Tech - Could you please check sir if the monitor is plugged in?"
"Customer - I'm sorry I cant do that right now we lost power to the building and I cant see"
another
"I cant get the cupholder to open !" (the cd tray)
Finally...
"It said insert disk 3 but only two would fit" !