I have a 9 volt battery that I assumed was dead sitting on my desk next to the computer. I also have a safety pin.
For no reason other than my natural inclination to fidget with things I had the safety pin on the battery, completing the circut I guess, but it wasn't sparking or anything. I was just fiddling with it and left the safety pin laying on top of the battery.
The battery got warm! oops. I don't know why exactly I thought it was appropriate to lay a piece of metal across battery terminals or whatever they are called.
Yes, I have been too busy doing things like this to post.
BTW I just touched the battery to my lips. Bright. Maybe I should go to bed now.