I was 18yo and just out of boot camp. One of my 25yo not sisters, Barb, came to visit me for a weekend. We shared a room at a nice resort motel. The day started off innocent enough with sight seeing and spending the end of the day at the resort hotel pool. I had a few beers and Barb had several cocktails. She was wearing a revealing provocative bikini and asked me to apply suntan lotion to her back. As I applied the lotion, I massaged her shoulders and back. She moaned with pleasure which excited and embarrassed me at the same time. When I stopped, she said, “don’t forget my bootie. I don’t want my butt sun burned.” She has a great ass, and with some degree of reservation, I started applying the lotion to her juicy butt cheeks. As I did so, she slightly raised her butt and slightly spread her legs. I could see her labia glistening and slightly protruding from her bikini. Her moist labia aroused me and embarrassed me. I could feel my cock starting to stiffen and, apparently, so could she, because she playfully said, “I can feel something nice, and it is not your hands.” I was shocked and speechless and quickly dove into the pool, to try to clear my head (both heads actually…lol).

By now, it was just about sundown and we were the last two guests at the pool. Barb got another cocktail and moved her lounge chair close to the edge of the pool. She raised the back up and assumed a sitting position with her long sexy legs spread wide, straddling either side of the chair. She had become slightly intoxicated and started to playfully flirt with me, applying lotion to her breasts and inner thighs, even going so far as to pull her bikini bottom tight and splitting her labia, slowly applying the lotion to her outer lips and playfully saying, “hey soldier, how long has it been since you have been with a woman?” Followed by a mischievous giggle.

I had gone into a kind of trance, gazing at her sexy body. Although I had jumped in the pool to calm down my cock, unknown to me, my cock had become rock hard, so as I got out of the pool my cock formed a huge “tint” in my swim suit, much to my sister’s pleasure, as she giggled and announced: “Oh my soldier, looks like you have a lethal weapon; your not going to use that weapon on me are you?” We both laughed as I toweled off and used the towel to try to conceal my “weapon.”

I wanted to grab a bite to eat, both because I was a little hungry, and because I wanted to get control of my sexual thoughts about my sister. However, Barb wanted to return to the room to get freshened up and go out to dinner later. I agreed and we returned to the room. Once in the room, there was definitely some sexual tension. Barb suggested that I shower first, so she could make some phone calls. As I showered, my thoughts returned to our flirting at the pool and the sight of Barb’s sexy body. My cock was rock hard, and I started stroking it, thinking that once I shot my load, I would stop having such taboo thoughts about my sister. Shortly thereafter, Barb completely naked, opened the door and pulled back the shower curtain revealing my now throbbing cock. She said: “I knew it! I knew you wanted to fuck me. You’re thinking of fucking me, as you masturbate, aren’t you soldier?” Again, I was speechless, as she knelt down and began sucking my cock, and saying: “It’s the least I can do to show my appreciation for your military service.” I wanted to stop her, but I could not stop her. In fact, her being my sister added to my arousal, and as she orally showed her appreciation for my military service, I started to relax, give in, and enjoy the experience. I even manage to speak (LOL) and asked: You like soldier boys don’t you Barb? She answered: “Yes, I certainly do, especially when the soldier boy is my sexy brother. Admit it, you are just as turned on as I am by the forbidden thought of you fucking me.”