"We're going upstairs to study," I quickly blurted out as nothing else better came to mind.
"Oh sure you were," Katie mocked me as she dropped her backpack on the couch. Katie was a few years older than me. Right now she was taking classes at community college since my mother didn't have the money for her to go to a 4 year school. Sometimes I wished we did. Older sisters could be such a drag, even though she always looked out for me. She would always tease me about girls, especially since I started going out with Amanda.
I looked at Amanda to make sure she wasn't embarrassed by what Katie had said. She had returned to normal by this time. Just to make sure that Katie wouldn't notice any further changes in my girlfriend, I wished that Katie wouldn't recognize any changes in Amanda's look or clothes.
While my mind was preoccupied with making the wish, Amanda took the defensive. "We weren't going to do anything. I've told Joe plenty of times that he's not ready." I looked at her with surprise. She was acting like I was the only sexually immature person in the room. Then I remembered my previous wish and realized that she was mature sexually.
Katie raised an eyebrow at her comment and challenged her on it. "So you're admitting that you're a slut?" I almost fainted in fear. She continued, "Because I've told Joe that you've been around the block a few times but he never listens to me."
Two things struck me odd about this. First, that in some strange way, my sister was looking out for me. She did always tell me that I deserved a great girl, and I guess in her mind someone who had been with others previously didn't qualify. But more importantly, I saw that Amanda was being aroused by this. Sure enough, her breasts swelled a bit to larger B cups, and she grew back up to 5'4".
And sure enough, Katie didn't bat an eye at the obvious changes. I was about to protest my sister's accusations, but Amanda cupped her hand over my mouth as I tried. "I wouldn't say I'm a slut just because I've had sex and I'm 16. If I was, do you think I'd be waiting around for Joe to mature?"
I didn't know how to feel about this. My girlfriend, whom I cared for deeply, was now unintentionally belittling me to make herself look good. And my sister couldn't seem to stand the fact that she was doing it.
Katie approached where we were standing on the steps. She came right to the foot of the staircase, as we stood on the third step up, and spoke again. "Maybe you're just using him for his brains. Or maybe you're using him for something else a little closer to home."
I couldn't believe what I was seeing. Katie was now starting to run her fingers through the buttons of her shirt. I looked at my sister, obviously coming on to my girlfriend, in complete shock. I glanced back at Amanda and saw she had jolted up to 5'8". Her breasts were now large D cups. Her legs were smooth and toned. Her skirt was so short it rode up to mid-thigh, and clung tightly to her very well rounded ass. The cut of her top also showed off her generous cleavage. It was also decreasing in size, as her flat stomach was exposed to the air. It seemed that my girlfriend was a little bisexual. I concluded only a little because, still clasping my hand, even more firmly now, she led us both down a step towards my sister.
I was in quite a bit of agony myself. My sister was extremely hot. I couldn't help but say that sometimes. It didn't help the fact that it was evident she wasn't wearing a bra. My cock was telling me that, too, as it was so hard I was afraid I might explode right there. Between my sister's coming on and my girlfriend's changes, I let my cock do my thinking for me. I wished that my sister would be willing to have a threesome with me and Amanda. I also wished that Amanda would be willing to do the same with my sister and myself.
The wish took immediate effect. Katie's hands began to run down to her pants. She inserted one of them underneath the waistband, letting it slip down to her awaiting pussy. Amanda again led us down one step so that we were right next to my sister. I noticed that she was even more aroused now. Her skirt wasn't even a skirt anymore. It was more like the skimpiest thong you had even seen. Her breasts also changed to the full DDD cup size I had wished for. The only thing holding them back anymore was a triangle top bikini that showed off everything but her areolas. Her erect nipples were clearly showing through the thin fabric. Still letting my cock think for me, I wished that she would retain her current figure no matter what.
Katie took a step backwards to allow us to descend the final step. Amanda finally broke the silence. "Or maybe you're trying to have me all to yourself!" she said.
Katie replied, "My mother was still a teenager when she had both of us, and has a pretty crummy job now. We've never had a lot. So we're used to sharing everything." She lifted her hand out of her pants so that the button holding them together popped open.
Apparently that was all Amanda needed to hear. She released my hand and literally ripped off her bikini top. With her breasts exposed, she said, "Then why don't you two share these?"
Katie took her hands and proceeded to rip her own shirt off, exposing her ample DD sized breasts. "My pleasure," she said. Sensing some apprehension from me, which I still had, she looked at me and said, "Joe, you know Mom always encouraged us to be a close family and to be open about sex. So don't feel weird."
She took each of us in her hand and led us upstairs to her room, leaving the shed clothing where it was. We reached her room, where she kicked off her shoes and without turning around removed her pants, revealing that she wasn't wearing any panties either. She whipped around to face us, showing a fully nude frame that any men's magazine would be proud to display.
Of course Amanda had one now, too. She reached for her thong. Feeling left out to this point, I grabbed her hand and stopped her. She gave me a puzzled look until I said, "Let me have some fun."
She smiled and with a sultry voice commanded, "Just rip them right off." I was only too happy to oblige. I grabbed the fabric and ripped it right off her enhanced frame. "Now you join the nude party," she ordered.
Feeling a bit submissive, I stripped as fast as you could imagine. "Come on over here," Katie said. She was now sitting on the bed in anticipation. Amanda and I joined her. The first thing she did was to take my face in her hands and kiss me with her tongue. "Just to make sure you're OK with this," she said. I responded by doing the same thing to her.
I always wondered what her breasts would taste like. So I released her lips from mine, lowered my head, and began to kiss her breasts. She began to moan softly, telling me that she liked the feeling. Amanda silenced her moans by kissing her lips. I started to suck Katie's nipple, and she moaned even as Amanda kissed her.
There was still a sense of wrong hanging over me. This was my sister whose breast I was sucking. I decided that there was no way I could ever actually fuck her. After all, Amanda was really my girlfriend. She was the person I desired.
I stopped sucking my sister's breast. She stopped kissing Amanda and was about to protest. "Just follow my lead," I told them. I laid my sister down on her oversized bed and beckoned Amanda to position herself over Katie. They both looked at me like I was weird. I placed my hands on Amanda's massive breasts and gently squeezed them. Feeling the moment, I ran my hands down her slender frame and reached her awaiting pussy.
At this point Kaite had leaned forward and once again began to kiss Amanda's lips. My girlfriend was bent over my sister in the exact position I wanted her to be. I straddled her, allowing my erect cock to slide over her heart shaped ass. Judging by her sudden intake of breath, I knew she could tell what I planned to do.
I took my cock and found her slit. I began to thrust slowly inward, and my first sexual experience started doggy-style. As my thrusting continued, she began to slip closer to my sister. Their liplock did not stop. Now Amanda began to run her fingers over my sister's firm breasts. She seemed to take the hint I gave them and her fingers continued to slide towards Katie's pussy. I started to thrust harder and Amanda's hand quickly found their target. She inserted her fingers into Katie's already moist slit.
Not wasting any time, she used the same motion on Katie that I was using on her. Almost in unison I was thrusting my cock in and out of her as she was thrusting her fingers in and out of my sister. Their lips had by now parted and both were moaning as loud as they could. I reached around with my left hand and teased Amanda's breast once more. Her moans grew louder as they did.
Suddenly Katie let out a scream. Amanda slowly withdrew her fingers from Katie's wet pussy, while at the same time still moaning as I continued. A few seconds later she too let out a scream of climax. I pulled my cock out of her and she collapsed on top of my sister. I too felt exhausted and laid down next to my sister, who had put her arms around my girlfriend. Amanda had a look on her face like she had never been pleasured like that before.
Katie said to her, "Not bad for your first time, was it?"
Amanda shot her head up and looked right at her. "How did you know?" She almost seemed embarrassed.
Katie smiled knowingly and said, "I just knew. I've been there before. Aren't you glad this was the first though?"
Amanda looked back at me, smiled deeply and said, "Yes." She practically lept on to me and kissed me passionately. After the moment passed, she said, "And to think that it all start--"
She couldn't finish the thought as we all heard the sound of the front door close. A voice called out, "Katie, where the heck are you?"