Had something flick up and hit the windscreen a few weeks ago. It contacted just under the n/s windscreen wiper blade, which I think is why it got cracked as the blade stopped it going anywhere, as I think otherwise it may have just glanced off. It was very loud so it was a surprise when the crack appeared.
Pain in the **** but at least I was covered by insurance, so only a small excess to pay to get it replaced.
Nice man from Autoglass came to my work and fitted it in about half an hour.