I’d hazard that it depends on the scar. Compare the following answers to “wow, where did you get that scar?!”
1) Well, I was out on safari in africa when our camp was attacked by a grizzly bear. I fought it single-handed, but before I throttled it to death with my bare hands it managed to catch me with a claw.
2) I was walking back from visiting my sick mother in hospital, when I saw an old lady being mugged. The ne’er-do-well had away with her handbag and I gave chase. He was no match for me and I soon caught him, but in apprehending him he managed to stick me with a knife. I held him till the police arrived and then lost consciousness. When I came to in hospital, I was told that I’d almost died.
3) Er, I fell off my bike.