Good excuses to tell people for self harm scars?

I used to be a cutter, a while ago, and my scars are still pretty visible. There on my lower arm, on the top so it's really easy to see, i can cover then with 3/4 length shirts. and there like, lines in different places. I don't want to wear makeup over them, because it can get expensive and im BROKE. lol. anyways, what is a good excuse i can tell people if they ask? or if there staring? i sometimes tell people i fell on barbed wire as i scooted my arm down it scratched me. poeple seem to believe it. it makes more sense when i say it in person.... ne ways what are some reasons i can tell people???? thanks!