Reading the linked story reminded me of my own adventure with my then girlfriend.
We were both thirteen at the time, and were just really beginning to feel the full impact of sexual desire. Our families had been friends for many years beginning with our parents college days, and we had been 'dating', i.e. going to the movies together. We were kissing, holding hands, and generally raising the temperture of our erotic engines when we finally got the opportunity which is described here.
It was on a warm summer day at a beach house. Our parents, siblings, and friends left us alone, and soon we were kissing ardently. I began stroking her vulva through her bathing suit, and felt the unmistakable soaking wetness which had drenched it. She was stroking my aching hard penis. During a break, suddenly she took my hand, and said, 'Let's get comfortable,' leading me to her bedroom.
When we got there, she stripped, I did as well and we resumed kissing, and pressing our nude bodies together. Next she lay down on the bed with me next to her lying on my side with her stroking my rock hard penis while I continued to stroke her clit. It was then that I felt her outer lips spread open and swell, an experience I shall never forget. I was so surprised by this that I stopped stroking her clit, and felt her now open swollen lips. Her pelvic floor seemed to have flattened out and her clit was sticking out as if it were a little thorn.
She hissed, 'Don't stop.' I returned to stroking her clit in little circles, she began to arch her back, and lift her behind off the bed. Her breathing came in gasps, and her entire body stiffened as she began her orgasm. I kept stroking away on her clit, now rubbing it vertically until she made me stop saying she couldn't stand any more. Then I rolled over on my back, and she resumed stroking my penis holding it so tightly that she was dragging the skin along with her fist. Soon I felt the beginning of the greatest orgasm I had ever had. It began with a flow of clear come followed by six or seven spasms shooting thick white sperm, and ended with a long oozing. We lay together for a few minutes languidly, and then began to clean up.