LOL! Many, many times, yes. My BFF and I discovered the joys of mutual masturbation at 12, and even today, she likes to cram a couple of fingers inside me to tickle my G-Spot! We’re both 17 now.
When we were 13 we'd do it in front of and with friends too.
Yes! My friends frequently would come over my house to relax in the pool and the jacuzzi. Also because my parents were very liberal.
One sleep over I invited like 10 of my friends and we watched movies and at night we got in the pool. We decided that we all were going to go nude and convinced the 4 shy girls that were very nervous.
5 of my friends and I were sexually actively and experienced and you could tell because we all shaved our pussies while the other girls had full bushes. This made them very curious about sex and masturbation.
They wanted to know how to touch themselves so we started to rub our pussies and show them how they should touch themselves.
Some of us ended up rubbing each other which was heavenly.
My boyfriend was always fingering me when I was about 12 and I loved it. If we had another friend over too then I let him finger me in front of them. Usually it would make them horny as well. Once he fingered me in front of my best friend and she started fingering herself while she watched, Another time he did it in front of his best friend. His best friend got his cock out and jerked off and came all over himself. LOL