I just found out about your site a few days ago. This happened this past summer after my first year in college and just shortly after my 19th birthday.
My sister is 2 years younger than me and is a senior in high school. She is a way cool and has become a total fox. The guy who ends up with her is going to be lucky. She's smart and beautiful. She doesn't really have a boyfriend now because she wants to go to college and not have anything to hold her back. I have seen her naked a few times, mostly when she was younger. Being my sister, there never was anything sexual between us.
In August, my sister had a sleepover at our house with three of her friends - kind of an end of the summer party. I hadn't seen these girls for a year and could not believe how they had changed. I guess their hormones must have kicked in during their junior year because they were all filled out. I had always thought of them as annoying when I was in high school but not now.
The night of the sleepover, I was in charge of the house. My parents had gone to dinner and a movie and weren't expected home until late. Our house is a bigger, 2-story home. My bedroom and bathroom is downstairs in the back part of the house. My sister's room is upstairs and so is my parent's room. The girls were all upstairs in my sister's room doing girl stuff. I was in my room on the computer and listening to music. About 10:00 I went up stairs to check on them. The door to my sister's room was closed and so I knocked and told them through the door that I was going to bed. My sister opened the door and I could see that they were all in their sleepover outfits. Long nightshirts and underwear (I was assuming), and watching TV. Like I said, these girls were totally fine. Tanned skin, great tits and firm asses.
I told my sister I was going to take a shower and go to bed. As I headed downstairs I heard the door close behind me and then a bunch of giggling and laughter. I turned off all the living room lights, turned the porch light on for my parents and then went to my room.
The door to my bathroom has a broken lock and when you close the door after about 15 seconds it slowly opens on its own about 2 inches and then stops - its always been like that. If I want privacy sometimes I put a shoe behind the door so it can't open. Since nobody was downstairs I didn't use a shoe this time. So here I am taking a shower and I decided to jerk off. I have a pretty decent sized dick and I like to masturbate in the shower. My shower and tub has glass sliding doors that you can see through. As I'm jerking myself, I happened to glance toward the door and see what looks like a pair of eyes looking at me through the crack. Thinking that this must be one of my sister's friends, I pretended not to notice her (since the hallway was dark - she probably thought she couldn't be seen). I held back as long as I could and then blew a huge load of cum. When I opened my eyes, the mystery person was gone. I toweled off and went back to my room, crawled into bed and tried to go to sleep with a big smile on my face.
About 15 minutes later, my cell phone rings. When I answered the phone it's my sister calling form the phone in her room. She told me that Stacy (one of her friends) wanted to talk to me. Without coming right out and saying it - so has not to let the other girls know what we were talking about, Stacy basically told me that she had seen me jerking off in the shower. She said she had gone down to the refrigerator to get a Coke and heard the shower water and saw that the door was open. I didn't tell her that I had seen someone watching me. It was exciting to know that she had seen me cum. Anyway, the phone conversation ended with her swearing not to tell anyone about what she saw. Again I tried to go to sleep, this time with an even bigger smile on my face.
Around 2:30 in the morning, I feel someone touching me on the arm. I was sleeping pretty good and it startled me. Here in my room were Stacy and Amy (another of my sister's friends). Stacy told me that my sister and the other friend (Monica) were sound asleep. Stacy told Amy about watching me in the shower and Amy wanted to see a guy's dick get hard. Well hearing that, it didn't take long for me to be rock hard again. Stacy asked me if I could make myself cum again for them. They both sat on the edge of my bed while I lay on my back and started pulling on my boner. Amy seemed to be in a trance when she saw my erect cock. Her parents are older and she doesn't have any brothers or sisters. I wondered if mine was the first dick she had ever seen in real life. I reached under my bed and grabbed a bottle of hand lotion I always kept and started working my cock. It was only a few minutes before I blew the biggest load of my life. 4-5 big squirts of cum that went straight up in the air and landed on my legs and chest. Stacy who was sitting closest to me wiped up some of my cum with her finger and showed it to Amy.
After I came, we talked for a little while. Both girls told me they masturbated. I told them how much I enjoyed cumming for them. When they finally got up to leave, Stacy turned back toward me and grabbed my hand and put it up under her nightshirt. She wasn't wearing any panties. She had a nice trimmed bush. I put two fingers in her dripping wet pussy. With my thumb I touched her clit and then I felt her kind of shudder and think she might have had an orgasm. I couldn't believe how wet she was.
I don't think they ever told my sister about what happened that night. At least my sister never mentioned it or acted strange to me in any way. I hope to see them again during school break. Every time I think of that night I get instantly hard. I hope to have more stories to tell in the future.