The girls arrived at my place just before dinner each carrying a bag. I couldn't resist the tease. "What's in the bags" I winked at Tina.
Tammy looked at me and said "Clothes and stuff.'
"Clothes?" I asked. "You're not allowed to wear clothes here, we spend all our time naked, unless we go out. Right Tina?"
"Absolutely!" she answered and reached up to start unbuttoning her shirt.
A look of pure horror came over Tammy's face. Seeing it we both burst out laughing and poor Tammy realized she had just been the butt of a joke. It helped to break the ice and make her feel more comfortable although. The girls settled in, Tammy put her stuff in the spare room and Tina carried her bag right into my room. Tammy was obviously shocked at this wanton display of impending sin, but she didn't say anything just watched wide eyed.
We finished off the day with settling in, dinner and then quiet television. After watching TV for a while Tina decided to get ready for bed. She disappeared into the bathroom and returned a few minutes later wearing one of those oversized "T" shirts that women wear for sleepwear. As she sat down with me on the couch again she said, "Tammy, you can get ready for bed if you want unless you plan on going out yet tonight."
With that Tammy got up from the easy chair she was sitting in and headed for her bedroom. She stopped halfway there and turned and asked, "Is it OK if I take a shower."
"Go ahead," I answered, "There is a towel for you behind the bathroom door. Make yourself at home."
She responded with a nervous smile and continued on her way. A few seconds later we heard the bathroom door close. At that sound Tina took my hand and placed it between her legs, under her T shirt. I was delighted to find she wasn't wearing any panties and I immediately set to work stimulating her with my hand.
I slowly applied pressure with my hand and gently rubbed her mound. She was instantly wet as I continued my ministrations to her pussy I could feel her juices running out of her and onto her thighs. I slipped a finger down and entered her. I fingered her through an orgasm and beyond. Both of us were to preoccupied to hear the bathroom door open later. Having caught movement out of the corner of my eye, my attention was drawn to the other room where I saw Tammy standing there with her mouth hanging open watching me finger fuck her sister while I had my tongue down her throat. I watched her reaction without letting on that I knew she was there and after a couple of minutes she retreated back toward the bedrooms.
About 5 minute later we heard the bedroom door slam and Tammy called loudly "Tina can I borrow your hair dryer?" I smiled to myself and before Tina could answer, I called back "Use mine, it's under the sink." We heard the hair dryer start up and run for a few minutes before it shut off and the door slammed again. Then Tammy called from the hall "Does anybody want anything from the kitchen before I come in?"
"No thanks." I answered back. It was obvious that she was trying to warn us she was coming into the room so she wouldn't catch us again. Tina had no idea that Tammy had walked in on us earlier and I was ready to split from keeping in the laughter.
The rest of the evening was just TV and a little talk, I invited Tammy to join us the following day. We had planned a picnic and hike at a local Civil War battlefield. She was thrilled to be included but Tina gave me a dirty look.
Once we went to bed I explained to Tina that if we were going to spend two weeks together it was better to make her a friend than ostracize her. That way she would give us our space when we wanted it and they would get along better when their parents returned, hopefully no more blackmail.
We made passionate love that night, calling out, moaning and groaning and everything else. It wasn't till the next morning that I realized we had left the door open. I wondered how badly we had kept Tammy up.
The next few days went smooth, Tammy settled in and the girls started to get along better. It was the fourth night we were together that I realized how close we were becoming.
We all went to bed as usual and as usual I did not close the bedroom door. We spent the normal amount of time having sex. We stroked each other, I went down on Tina and ate her pussy till she orgasmed then I got her up on her hands and knees and fucked her from behind, then before I was finished I lay down and she rode me until we orgasmed together. I was satisfied but Tina was a nymphomaniac and wanted more, so she crawled over and started to suck me into her mouth to coax me dick back to life.
It was while I laid there on my back getting a very satisfying blowjob that I glanced over at my dresser and in the mirror above it I saw a sight I will never forget. In the mirror I could see Tammy in her bed. She was stark naked, exposing her beautiful 18 year old body to the air and the moonlight spilling in through her window and falling across her bed. She had her right had furiously fingering herself while her left was pulling at her nipples. It was plain to see that her gaze was fixed the same place mine was, on the mirror. She was watching her sister suck my cock and bringing herself off while doing it.
The thought of this little nymph watching and jacking herself excited me and I figured we would give her something to watch. I urged Tina's legs over me so she straddled me in a classic 69 and I went to work on her pussy. I ran my tongue up and down he slit, sucking her lips into my mouth then flicking at her clit, then stabbing into her hole and wiggling it around. A few minutes of this attention and Tina exploded on my face. I slurped up as much of the juices as I could and turned her around so she could ride me again. All the while I kept an eye on the mirror watching the watcher. Now I started to talk to her in a loud voice. I told her how much I loved the feeling of her pussy around my cock and how good she tasted, how I loved when she came in my mouth, and on and on. The effect on Tina was obvious as she sped up and was impaling herself on me with a vigor. From what I could see it was having a similar effect on Tammy, as she was now ramming what had to be at least 3 fingers into her cunt and nearly pulling her tits off.
