I'm Dan. I'm 18 and I live at home with my Mom, Dad and sister Rachel. I'd like to tell you a bit about my family (they may come up in this story).
My Mom is called Janet and she 43. She has long brown hair and an 'athletic' body. Slim, small breasts. I had seen her in a bikini plenty of times and often she would go around the house in just her underwear so I had seen enough of her to know (not that I would look...much).
My Dad is called Martin and he's 43. He has a little middle aged spread but other than that a handsome man.
Rachel is 20. Her hair is brown naturally but she bleaches it and has it cut shoulder length. She has the same slim body and small breasts as Mom. She also shared my Mom's habit of going around the house in her underwear (I did look much).
We were all sat around the breakfast table talking and Mom asked me "Is tonight your work party?"
I worked as a mail boy for a lawyers firm and we were having a staff party.
"Yes but I don't think I'm going."
"Why not? I thought you were looking forward to it."
"I was but I kind of dug myself into a hole. I was trying to impress everyone at work and told them all I had a hot girlfriend. If I turn up alone they'll know I made it all up."
"That was silly but can't you just tell them she's sick or something?"
We talked about my situation for a while. Mom was being very comforting and helpful in the way Moms usually are and Dad and Rachel were making fun of me in the way Dads and older sisters usually do. Eventually it was Mom with a kind smile and stern words about self confidence who convinced me to go.
Later that day I was ready for the party (I mean dressed for it but still not keen). I was nervous about what to tell my friends about my 'girlfriend'. Mom and Dad were sitting on the couch together when I was about to leave.
"I'm now going, wish me luck." I said to them.
"Wait! I'm coming too." I heard my sister say behind me. We all turn to see Rachel stood there looking sexy as fuck. She was wearing a red dress with a low V cut showing a lot of bare chest and clearly she wasn't wearing a bra. It was a short dress stopping only just below her ass showing pretty much all of her nylon covered legs. Her red stilettos and red lipstick both matched her dress.
"W..what do you mean you're coming?" I managed to stutter whilst drooling.
"Well it was stupid of you to lie about having a girlfriend but I'm not about to let anyone make fun of my loser little brother, that's my job. I'm going to the party with you and we'll show them your 'hot girlfriend'."
"Aah, that's sweet of you." Mom said. I was still struggling to speak (and struggling to hide that fact).
"That's because I'm the best sister. Wouldn't you agree Dan?" She asked me with a smile.
"No chance they'll believe it, she's too hot for for you." Dad joked.
"Actually, you are the best big sister. Thank you Rachel, you're a life saver."
"Tonight I'm the best 'girlfriend' ever, and you're going to owe me big for this, let's go."
As we walk out to the car I was feeling good about this plan. Nobody at the party knew any of my family, Rachel was definitely hot. This was going to work. When we got to the car I opened the passenger door for Rachel then got in to the drivers side and set off.
"I think we should clear up a few details before we get there." Rachel started "Firstly did you tell them your girlfr.. I mean 'my' name?"
"No. All I told them was that you were hot and you've got that covered."
"Good, it'll be easier if you can call me Rachel. Most brothers don't call their sisters hot though." I suddenly realized how blatant I had been and blushed. "Don't worry, I am hot." she laughed.
The rest of the journey we cover all the details like how long we'd been together, how we met. We arrived at the venue the firm had hired for the party and I parked the car but before we got out Rachel turned to me and said "There's one more thing we need to do."
"What's that?" I asked.
"We should kiss."
"Kiss? Why?"
"Well we'll need to look comfortable kissing so we should practice before we go in."
"We've kissed each other lots of times, it's no problem."
"No stupid. Not a brother sister kiss, a girlfriend boyfriend kiss."
It honestly hadn't occurred to me that in order to pretend she was my girlfriend I would actually have to pretend she was my girlfriend, kissing and all.
"Can we?" I asked "Is it OK for siblings to.."
"It's fine" she interrupted "and we're going to have to if we're going to convince people. Just relax."
We both turned in our seats a bit and leaned in for a kiss. As soon as her lips touched mine my whole body tingled electrically. It started as just a little peck on the lips but then, with Rachel taking the lead, we opened our mouths and our tongues touched. We were then having a full on passionate kiss. It was amazing. Rachel was a great kisser and the fact she was my sister seemed to make it even better. After a moment Rachel broke the kiss and we looked at each other smiling. I suddenly became very aware of my erection and hoped Rachel wouldn't notice.
"Wow, you're a better kisser than I thought you would be." Rachel said.
"Um, yeah you're pretty good as well." I said trying to play it cool.
"With an erection like that it must have been better than 'pretty good'." Rachel glanced coyly at my crotch.
"No, it's just, ah, well." I shifted in my seat.
"It's fine. Boys get erections kissing hot girls. It's normal. Now lets go inside."
Inside the party was well under way with drinks and music and a dance floor and everything you would expect at such a function. I saw my work friends and all of them were blown away by Rachel. Most of them assumed my girlfriend wouldn't be 'that' hot, a lot guessed she didn't exist at all. Rachel played the part perfectly, so well in fact even I started to believe she was my girlfriend. I may have taken advantage going for as many kisses as I could through out the evening and knowing she couldn't really refuse, she was my 'girlfriend' after all, but Rachel didn't seem to mind. If we were stood together talking to other people I would put my arm around her waist and even put my hand on her ass for a quick squeeze of her firm buttock and still Rachel played her part.
What surprised me even more than how well Rachel was getting on with everyone else was how well she was getting on with me. We had always gotten on well but my sister was turning out to be the best date I'd ever had.
Near the end of the night Rachel and I were sitting at a table alone talking. The music was loud enough that we could talk without being overheard.
"So how do you think I rate as a 'girlfriend'?" she asked.
"Ten out of ten, I see why all my friends fancy you." It was the way she looked at me that made me realize what I'd said. "I mean from their view, if you weren't, well, if I wasn't..."
"You're turning out to be a pretty good date too."
The DJ then put on a slow romantic song, a sign the night was coming to an end. I stood up and held my hand out for Rachel to take. She gave what could only be described as a seductive look, took my hand and stood up. I lead her to the dance floor and put my hands on her hips, she put her arms around my neck and we moved close together. As we danced my cock grew hard and I felt it press against Rachel.
"I'm sorry.." I started and tried to pulled my hips a little back.
"Ssh, just dance with me." Rachel said and pushed our hips back together then kissed me.
After the song the party ended. Everybody said their goodbyes and Rachel and I went back to the car. On the drive home we kept on talking just like we had all night even though there was no one around to play up to, we were just having fun. We got home, went in and upstairs. Our bedroom doors are opposite and we were stood between them.
"I suppose this is good night. Thank you for tonight, you were a great date." I said.
"You ARE a great date as well." Rachel pulled me in for another kiss. This time when our bodies pressed together I didn't worry about my erection and let it press into her.
The whole night had been like some strange dream. She was my sister but she had been acting like my 'girlfriend' and now we were at home she should have been my sister again but instead we embraced like lovers.
