What do you mean it's a "used" computer? Did you use all of it's "computing"?

Growing  up in Ontario we used computers all the time.  Even though there wasn't much to do with them, they made great walls for our gerbil mazes.  The computers were good, but we also used computer keyboards, and we used computer monitors as well.  The first thing you have to understand about gerbil's is they don't understand computers or computer equipment.  They didn't get that when they peed on our terrain obstacle (also known as a keyboard) that we either had to either buy an entirely new (used, we were rich, but not that rich) computer equipment or that we'd have to some sort of electronic repair service.  Thing is about the dudes who do electronic repair service is they:

1. Don't like it when you tell them the piece of equipment you're working on was peed on by anything.
2. Can't fix certain things once they've been doused in urine. 

So, we finally stopped using keyboards as terrain obstacles. 

Later when I was in college I worked at a electronic repair service dept. for a software company and used computers; laptop and desktops to diagnose issues with high-end thermometers that they built for the govt.