I had to pull my fridge away from the wall today for technical reasons and found this fellow down the back. No idea how it got there. I don't keep onions anywhere near the fridge. I'm guessing he can't have been there too long. He was in a plastic bag so the shoots couldn't grow straight.
The bulb is obviously a bit shrivelled, but the roots and shoots look healthy. I've potted it on my balcony just to see what happens.