I think I’ve told this one before:
When my wife was pregnant with Pope Kid the 1st, a friend gave us a small music box - one of those ones that’s all metal with the workings exposed so you can see everything going around and wound up with a small crank handle.
My wife had been playing with it during the evening and then put it on the shelf of the nursery and went into the spare bedroom to read and do some study. About an hour later I was out in the kitchen when the music box started playing and I called out to my wife, teasing her a little bit for playing with the shiny object 
Turns out she was still in the spare room surrounded by books, paperwork and her laptop :eek:
Debunk: The spring in the music box had run down until the tension was contained by the gears. As it was a cold night the metal parts had contracted enough to let it play for a few more seconds before stopping again.