This story is true, to the best of my recollection. It was, however 20 years ago, but I'll always remember it because I'm sure it helped shape my sexual desires later in life... I'll get to those in another story... Also, I changed the names of everyone involved.
I was an 18 year old high school senior when my friends introduced me to Mary, another senior from my school. Mary and I hit it off, and before long we started dating. We would eventually leave high school and get married, then divorced 5 years later, but I didn't know that yet. For now I was a dorky 18 year old virgin who jerked off a lot, but had very little experience with naked girls in real life, and she was a very cute 18 year old girl, with long dark curly hair, a nice curvy figure, and C-cup breasts that I very much wanted to see.
After a couple weeks of "dating" but only seeing each other at school, and seeking out any privacy we could find so we could make out, Mary invited me over to her place after school.
I found out that Mary lived with her 19-year-old older sister, Suzy, who graduated high school the previous year and was job hunting; and her mother who worked long hours during the day, and usually didn't get home until around 11 o'clock at night every night. The three of them shared a two bedroom apartment, which meant that Mary and Suzy shared a bedroom.
Mary brought me over to her apartment, introduced me to Suzy, and told me of their living situation. As long as I was gone when their mom got home at 11, we could do what ever we wanted! That first day we stayed in the living room, for Suzy's sake. For the appearance of propriety, but that didn't last long at all.
The next day I came over after school again, and Mary and I quickly found ourselves on her bed with the door closed, making out with her top off, and my pants off! (The first time I got to see her lovely breasts!) This first day was only kissing and hand stuff, and her panties stayed on. We were both too nervous to take it any further just yet.
Here's where things started to take a more interesting twist. After about an hour Suzy barged into the room without knocking. it was her bedroom too, after all.
Mary quickly covered herself with the blanket, but left nothing for me to cover up with, leaving my hard dick exposed for both Mary and Suzy to see.. and yeah, Suzy saw it...
Suzy said she was looking for something she needed, but we didn't have to hide what we were doing, she knew and didn't care.
For the next few weeks I found myself going over to Mary's apartment every day after school, and we would find ourselves in Mary's bed, with no parental supervision. Knowing Suzy didn't care what we did, It didnt take long before we took each other's virginity.
It also didn't take long before we got so casual about not hiding it from Suzy that we wouldn't bother closing the door, or Suzy would enter the room while we were in bed, and it was like no big deal... Then it happened...
One day, Mary and I had just had sex in Mary's bed. we were laying together, cuddling, when Suzy invited us to watch something on TV with her in the living room. I don't remember what it was, but Mary really wanted to see it, so we got dressed and made ourselves comfy on the couch.
While we were watching it, Marry and I cuddling on the couch, Suzy chillin by herself in the recliner, Mary reached over, un did my zipper, pulled my dick out, and started casually playing with it, like it was some sort of fidget toy.
As she was doing it she asked if it was okay, I said "sure, but what about Suzy?" We apparently were not all that quite cause Suzy said she didn't care... So I spent the rest of the night with my hard dick out in front of both Mary and Suzy!
Before I knew it, every time we got to her place, as soon as we walked in the door, Mary would kiss me, and ask me to take my dick out, right there in the living room; and want me to leave it out the entire time I was there, whether Suzy was with us or not. It was like Mary was obsessed and fascinated with my dick, and constantly wanted to see and feel it, and didn't care at all about if Suzy could see it or not.
It didn't take long before she stopped asking, and as soon as we walked into her place she would just unzip my pants and take it out, and I would spend the rest of the day with my dick just on display for both my girlfriend and her older sister.