What should you do?
I ask, because this happened to me in the car park at work this evening, only I was the guy fiddling around in the boot. What this guy did was he gave me a slightly sheepish smile. But what am I supposed to do? Go ape-shit? I smiled back, almost reflexively. We've all done it, after all. It's just his bad luck that I happened to be standing right there when he did it to my car. So I smiled at him, silently absolving him and letting him know that it could have happened to anyone. Marvel at how phlegmatic I am being! This car is 4 months old! I am so calm. I am a zen warrior.
Then I stood there, waited for him to leave - going so far as to pretend to be opening the driver's door to get in - and as soon as he left, I nipped round the other side of my car to have a closer look. There was nothing to see. It was just a gentle little ding. It happens all the time.
On reflection, I'm not sure a sheepish smile was enough penance. I know I blew it by smiling back, but come on! Dude! I was standing RIGHT THERE.
But what do you do? What would you do?