One hard thing to explain to teens is how legitimately exciting it used to be when someone would wheel in an overhead projector.
The chef of the upscale restaurant I manage collided with a waiter one day and spilled coffee all over our computer. The liquid poured into the processing unit, and resulted in some dramatic crackling and popping sounds. After sopping up the mess, we gathered around the terminal as the computer was turned back on.
"Please let it work," pleaded the guilt-ridden waiter.
A waitress replied, "Should be faster than ever. That was a double espresso."