My name is Will, and this is the story of something I that I never in my wildest dreams thought would happen. My girlfriend and I had been together for about 4 years, we were both 22 and recently graduated from college. We had a nice little apartment in the city at the time. We were quite happy, and had a fabulous sex life. My girlfriend, Tracy, is a sexy blonde about 5'6". She has a tight, toned body with nice firm B cup tits and a great ass. We were both pretty sexually open, and had fantasized together about having a threesome with another girl, but nothing had come of it as of yet.
One weekend Tracy's sister Nikki came to visit. She was on break from her college, where she was a sophomore. Nikki was just as hot as her sister, in a slightly different way. Nikki was darker blonde, about 5'5", with softer features than her sisters. She had amazing C cup tits, but a smaller ass then her sister. I had often thought about fucking Nikki, or fucking them both at the same time. I even admitted to having a dream about it to Tracy, and surprisingly she took it in stride, saying, "how could you help it when we're both so good looking?" with a wink. In fact Tracy admitted to having the occasional naughty dream involving her sister.
Nikki arrived on a Friday afternoon, a little upset about a fight she was having with her boyfriend. Tracy and I sat her down to talk about it. It was mostly the two girls talking but I picked up that the guy was being an asshole to her, and that she didn't think she would stay with him because, as Nikki put it, "he's got a small dick anyway so he's doing me no good!" We managed to cheer her up, then we all went out to dinner and had a great time. We decided to just relax that night and watch a movie.
When we got back the girls said they were going to change into comfortable cloths to watch the movie, so I did the same. I threw on some workout shorts and a T-shirt and plopped down on the couch. A few minutes later Nikki and Tracy came in. Tracy was wearing thin blue pajama pants worn low across her hips and a tight white tank-top, obviously with no bra. Nikki had on some dangerously short cotton shorts that showed off her ass and a t-shirt, also without a bra. Tracy sat down in our big lounge chair and put her feet up, while Nikki sat down next to me. Nikki was always really comfortable physically with me, always giving me hugs and things, and Trace didn't think anything of her sister sitting next to me.
I turned the lights off and started the movie. It was pretty late, and Tracy seemed to fall asleep in the arm-chair quickly. Nikki, too was getting tired and lay down on the couch, putting her head in my lap. Now this was too strange, I knew how comfortable she was with me. I didn't know if she was asleep or not, so I just tried to keep calm with this cute 19 year-old's head inches from my dick. Unfortunately there was a sex scene in the movie, with some pretty graphic stuff, and I started to feel myself get hard. I was praying that Nikki didn't notice, but those hopes were dashed when she slowly turned towards me. To my surprise there was a little smile on her face.
"Getting a little excited, huh?" She said.
