This happened a few years ago when I was a freshman in college. I was dating a girl named Trisha who was blonde, blue eyed, and had a swimmers body. Well proportioned and at 5 foot 7 she had the most perfect round bottom I have ever seen. She and I loved the beach and swimming and her parents had a large backyard with a pool and spa. Trisha had a younger sister, Lori, who was 18 and almost as hot as her older sister. Lori was dark haired, with fair skin and perfect c-cup breasts. She knew her body attracted the admiring looks of men and her open personality attracted the attention of the opposite sex. She always had an easy smile and she would often laugh about her catching us making out on the couch or in Trishas bedroom. One night we even had a very revealing discussion between the three of us about sex and our various experiences. Lori admitted to masturbating on a regular basis and that she lost her virginity to her boyfriend at 16. She also told us she could come close to an orgasm when a guy would fondle, kiss and suck her breasts and nipples.
The weekend after our 'discussion' the sisters parents went out of town for a weekend getaway and entrusted the house to their daughters. Trisha and I had been swimming in the pool and were relaxing in the spa when we started kissing. This led to some touching and soon we were both nude, Trisha grabbing my erect cock and began stroking me under the water. My hands were caressing her breasts as our breathing got heavy and I suggested we go inside to finish what we had started. What we didnt know was that Lori had come home and gone up to her room to change. Hearing us in the pool she had been watching us in the spa for several minutes. Being the aggresive one, she put on her bikini and came out to get a closer look.
Trisha was startled when she approached the spa, worried that her little sister would see what we were doing. Lori laughed and said ' Trish, I know what your doing under the water. Its pretty obvious.' My hand had made its way inside Trishas soaked pussy and I was gently fingering her erect clit. I knew she must be close to cumming because she loves to be fingered while we kiss. I think I surprised both the girls when I suggested Lori strip and join us. Honestly I didnt think she would, but she boldly dropped her top and pulled down her bottoms. She bounced into the spa with a splash and leaned over to give me a kiss. My left hand went to her breast and she kissed me deeply as I fondled her. Trisha moaned loudly as she began to cum. She is not quiet when she has an orgasm and that night was no different.
As she came down from her climax, Trisha took her sister by the hand and pulled her to the edge of the spa. 'What Lori has never told you, Jim, is that she likes her ass spanked,' says Trisha. ' 'Show Jim your pretty ass now,' says Trisha as she pushed Lori down at the shoulders to the deck which caused her bottom to stick up in the air. Her bottom parted and her shaved pussy lips with her tight little anus peaked out from between her round cheeks. I stood up in the water and spanked her wet butt twice with my open hand. Lori yelped and looked back at me as I did it again. The girls then realized I was totally exposed with my erect cock bouncing in the open for all to see. Lori's eyes got big as she stared at my sex. Trisha jealously said,'dont get any ideas little sis', that penis is all mine.'
Without hesitating, Trisha again grasped my cock and masturbated me, at first slow and deliberately but then more firmly and going ever faster. As I grew harder and more excited, my hand roamed over the slick naked rear of little Lori, then darted between her legs to touch her labia. As my fingers penetrated Lori's pussy lips, my thumb teased her anus and Lori moaned quietly. Her pussy was now slick with wetness as I moved my fingers faster in and out of her lips, sensing that she would cum very soon. When she did, she sounded much like her sister. Trisha's hand had worked its magic too and I shot my load into the water with a load groan of satisfaction.
This was the only time we had a sexual encounter with the three of us. It will always be one of my favorite memories.