Purchasing tractor parts last week.
The owner was having trouble with his ancient POS system. After a couple minutes of swearing at technical help, and at least one "turn it off and then on again", he hung up the phone and dug under the counter and came up with an old pad of blank invoices. He allowed as to how he would have to hand write it because the computer was broken. Being me, I asked if I could have a look at it. He looked at me funny, because he's only known me as a rancher/farmer, but said OK.
I came around the counter & eyeballed the situation. Turned out the mouse didn't work. At all. Just an immobile mouse pointer in the center of the screen. I showed the guy the tab key and a couple other keyboard shortcuts for future reference, and eyeballed the system. The drivers were loaded, and running. Probably a dead mouse (tractor parts counters are rough on everthing). I just happened to have a spare serial mouse out in the truck (don't you?). Pulled the mini-maglite out of my pocket & dove under the counter to swap 'em out ... only to discover that the original mouse had managed to work itself loose. So I plugged it back in, and all was well with the world.
Well over ten years of daily use, and the computer had to wait until I was in the shop to spit out it's mouse. Now one of the biggest gossips in the county knows I'm a computer guy. Hopefully he'll keep it to himself ...