It was in my stocking this morning (we still do stockings): a can of Volvo Life Paint. My wife mentioned it to me in the summer but didn't share this video, and the idea of spray-on reflective paint like this was so out there that it clearly didn't stick. And then this morning there was this can in my stocking. So I looked it up and saw this video (I'm on my phone, so I can't do a proper link: https://youtu.be/CfWzeGlaFvI) and said a big, "Oh!"
I'll post a reply to this when I've had a go with it (the rain may wash it away) but it was just too impressive not to share right now given the potential to spare someone else a serious injury.
Merry (and Safe!) Christmas!