depending on where it is, you could wear clothing that covers, though i imagine you'd have thought of that. Jewelry, or make-up though if it's still healing it could get infected..... Could you perhaps say where the scar is, so we can get an idea of how to cover?

ankle i HAVE to wear shorts and sandles its for some stupid play thing at school that i was forced into doing idk y

When I get caught in situations where I cannot cover scars I think of a good story to explain how I got it. I hope that people won't find it but if they do and they ask I'm usually ready with a reasonable story to explain it.

Make-up, it's probably best, Stage make-up should work, it's certainly thick enough, though you should take it off soon as possible. unless you can work something into your costume...
And for after, if there's a cast parts, I'd bring a band-aid, Something with an amusing patterns to distract people from what's under.

im a guy its a mini play so theres only like 10 people and i own no make up and have no clue how to put it on

Which brings us back to my idea... Just make up a story. It's a lot simpler.

a story will work..... for awhile, i got a bunch of my friends to tell my parents that i fell down at a party that we had. and they belived me
until my friends told me to go to the counseerlor
but besides that it workedout great