I use the cigarette lighter for my cell phone. It was unplugged (opened).
I was cleaning my car using a vacuum. As I was cleaning the floor I spotted a penny. Being the lazy sob I am, I picked it up and tossed it up on the seat. Crap. It bounced into the open cigarette lighter. Guess what? Copper conducts electricity. Pops goes the fuse. It would not have been very bad but I did not notice it until later. The phone would not charge and a light or two were out.
Dumb. This was a small cost of only a fuse. It just goes to show you how things can happen.