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.