When I was 13 I stole a purple thong from my sister and wore it under my sweatpants at school even though I'm a guy.
I heard girl underwear feels a lot better on the skin? Is that why you did that?
I wore it to laugh at girls, I wasn't aroused by thongs, I haven't worn one for pleasure since.
There's really no good reason to steal anything from anyone, and especially not a thong from your sister. Wearing underwear that isn't yours is not a normal thing and you should have never done that-- you should tell your sister what you did and hope that she is able to forgive you, even if it was a long time ago.
That's fair.
You can always buy one for yourself if you like the feeling. I'm sure there are female underwear options out there that looks like a brief.