My first ever sexual experience came when i was 15. One Saturday night my parents went out to a dinner party leaving me and my younger sister of 13 years, Andrea home alone. I had always known she was pretty but never imagined that we would get together. At the time she had shoulder length brown hair, cute little breasts, and a perfect ass which was admired by all the boys in her grade. My friends used to tease me about my hot sister and what they wanted to do to her.Since neither of us had any plans for the night and it being a warm summer night, we went out for a swim in the pool in our backyard. I got in the pool first while Andrea was still inside changing into her suit. When she came out she was wearing her blue two piece suit which made me instantly hard. I couldnt help but stare at her cute little body as she entered the pool. I was glad that she couldnt see my raging boner underneath the water. We swum around in the pool for about an hour until it got dark out, so we decided we would go in. Since my cock was still as stiff as a rock, I got out first so there would be less chance of her seeing it. As soon as I got out of the pool I went straight for the house because I forgot to bring a towel. However, when I tried the door handle, it was locked. By this time Andrea was out of the pool and walking to her towel. This beautiful sight ensured that my boner wasn"..t going away anytime soon. I decided that I would go around the house and check the other doors and windows for a way inside. When I was leaving I saw Andrea looking at the bulge in my bathing suit.I went around the house and checked every door and window without any luck. I was about to go back to tell Andrea when something caught my eye inside the fence. Peeping through a hole in the fence I saw Andrea with her hand down her suit fingering herself. I couldn"..t believe what a lucky view this was. I pulled my suit down to my knees and started to masterbate while watching her finger herself. After a little while Andrea reached her orgasm and I was just about to release my load, when I felt a hand grab me by the shoulder and turn me around. To my complete horror it was my father back from dinner. He looked furious and said that there would be punishment for this kind of behavior. My father pulled me into the backyard by my ear with my bathing suit still at my knees. Andrea looked like she was going to have a heart attack after seeing this sight with her hand still in her pussy. My father told us that he had a special punishment that he was saving for a time like this.He brought us up to his bedroom and locked the door. We were all alone for the night because my mother was staying at her sick mother"..s house that night. He made us both take off our clothes and lie on the bed. I couldnt help but get another boner from seeing my sister but she didnt seem surprised after seeing our dad act like this. Now my dad took off his clothes as well and came over to me. He told me that I would get my punishment first. Before I had time to react he stuck his cock in my mouth and told me to suck on it. When I tried to pull my head away he told me that if I didnt do this I would get a worse punishment. I decided to go through with it and that maybe it wouldnt be that bad. I did exactly what I had seen people doing in my porno videos and my dad seemed to enjoy it. After a few minutes he told me to get off and he shot his load onto my face. It felt warm and sticky and I wanted to wipe it off but he said I had to leave it there.Now it was my sisters punishment. My father told her to do the same thing to me. I couldnt believe how good it felt when she sucked my cock. It was a dream come true. I didnt last very long though. After about a minute I pushed her away and came all over her face. We both thought our punishment was over and both scrambled to cover our naked bodies, I guess it was a natural reaction even after what we had just done. However, my father had other plans for us. He told us we had to eat the come off of each others faces without using hands. We hesitated at first until our dad started yelling at us to hurry up. Our first attempt, we just lay next to each other and tried to lick the come off of each other but this wasnt working. Andrea told me to lay on my back and then she lay on top of me. Her small body felt so good on top of me that I was actually enjoying it, as was evidenced by another boner against my sisters leg. Now that we were in a good position my sister lapped up my dads come from my face and she seemed to like the taste of it too. Her tongue licking me felt nice on my face in a weird way. Then we flipped over so I could clean her off. I didnt like the idea of eating my own cum but once I had my first lick it actually tasted alright. I slurped up my own juices saving the last glob that was on her lips for last. When I went for this one, we started kissing and tasting each others cum flavored mouths.Finally, my father told us to go to our rooms and stay there for the rest of the night. The first thing I did when I got to my room was beat off. I couldnt stop thinking about my Andreas body. We didnt discuss what happened between us over the next few weeks. Everyone just pretended it never occurred but I could never look at my sister the same way again.