I once parked in a space in a motorway services right on the end of a completely empty row of spaces. As I was eating my scotch egg a car drew up and a woman got out, she opened her back door to get to her dog and "slam" shee opened it straight in to my car!!
"Oops, sorry" she said. I got out and amazingly it had hit a corner of a panel and not the flat surface so it didn't dent.
I said "that was a stupid thing to do, if you had dented it you would have paid for it". She looked at me puzzled.
So I had to say again "If you had damaged my car through your careless behaviour you would be paying for it". Still looks of confusion.
At this point I got a gun out and shot her dog. "Oops, sorry" I said.