I am a mature married mum now in the UK but this memory is from my younger days when I was 15 and Barry, my then boyfriend was 16. We had already masturbated together, getting great pleasure from watching each other and seeing how the other one did it, sometimes lending each other a hand.
Our horniest experience ever, happened at a party at someone's house one Saturday night. It was quite late and the lights were down low, music playing and couples were paired off, dancing smoochily or lying around cuddling. Barry and I were lying face to face on the carpet among many others couples who were embracing.
I felt his hand between us, hidden from view by our close bodies, and he slid it up my leg, under my dress and caressed the front of my panties. It felt naughty doing this secretly in a room full of people. I could feel that my dress had ridden up at the back and I wondered if others could see my little pink panties. As I got wetter he slipped his fingers in the leg of my panties and started rubbing me properly, massaging my clit and sliding his fingers inside me.
Not to be outdone my lower hand sneaked closer to him and unzipped his trousers and felt his hard cock in his underpants. I managed to manoeuvre it out into the open and rub him slowly, pulling the skin back from the throbbing head. Meanwhile he was continuing to play with my pussy in just the way he knew I loved.
I came first, biting my lip to stop myself crying out but I know that my body shuddered and I wondered afterwards if anyone had seen me come. His hand then moved to replace mine on his cock and I held his balls as he rubbed himself until he shot his come over the carpet where we were lying.
This was a first for us both doing it so publicly but it was the start of us masturbating together in many other risky places.