It's all in how you tell it. You have to wait for the opportunity to arise, and then you have to tell the story just right. Let 'em be impressed for that half-second. No explanation forthcoming. Scar stories are the narrative eclat of many a ninth grader.
Adults tend to be more reticent about scars, more philosophical.
In his twenties, Peter has a wound litany as voluminous as Wayne's, and I think, truth be told, he revels in such revelations as much as Wayne does. That's the tone even when he tells you about the cannon that blew up in his hands. The doctors don't know. It impresses his high-school students. Most adults don't even inquire, though.