I disagree. A scar means an injury, probably a serious one - maybe an accident, maybe assault, maybe self-harm. If someone has a funny or weird story they want to tell about how it happened, they will do that unprompted.

Same. I have a big scar from a self-inflicted injury and I like saying “Shark attack.” Lots of people have found it appropriate to ask me about it, and there’s apparently a sizeable overlap of the rude and credulous. Who are these assholes and were they raised by rude wolves?!