A few years ago, I was cycling down three steps, which I had done many time before. Though this time my front wheel went to my left while I wanted to go right. So the end result was a face plant and broken clavicle.
The first 30min after I was sure everything was ok. Just rather sore, some cuts here and there but nothing major. It was only when I got out of the shower that I noticed that my left shoulder was not looking like my right.
Bit of a cheat this, as it is a photo of the x-ray :)