Someone brought me their computer this weekend because their mouse wasn't working. They had replaced it, but the new one wasn't working either. I was hooking up the computer in my workshop to see if I could find out what was wrong. As I hooked up one of their mice I notice that the pins in the plug had been smashed down flat. The new one and the old one were both like that. I photographed them with a good mouse on the right side so you could see the difference. So, I found the source of the problem (and had a good laugh) without ever turning the computer on. Rembember, be gentle. I tried bending the pins back with tweezers, but they're beyond repair. Click on the image on the left to see a bigger version.

Update: On Josh's suggestion, I made a poster with this image.