I had lived with my flatmate Karen for about four years, and we had sex often. It was almost a ritual. After her boyfriend or lover had left, I would climb into her bed and fuck her one last time. Sex with Karen as excellent she was physical, open to experimenting, and loved public sex and showing off. What I loved most was that she would have an orgasm, and you couldn't help to hear it even outside. She knew this, and it would excite her to know someone might listen to her fucking.
It was always a challenge to find an opportunity for us to have sex when she had a boyfriend staying overnight. However, one occasion, I heard her go to the bathroom after sex, so I waited and followed her to the bathroom, where I fucked her sitting on the vanity. That was one of the only times she came quietly.
Life became fascinating when Karen received a call from her younger brother that he had his mate transferred to work in the city. He asked if Karen would show him around and help him find a place to live. At the time, Karen was 25, and he was just 18 and would arrive by bus the following Saturday.
Young Mark arrived on Saturday morning. Karen picked him up and returned him to the apartment to drop off his bags. She said she would show him the sites and swim at the beach as it would be hot. She asked if I would like to join them because the barracks were near the beach, and she wanted close and easy parking. The other advantage was that a section of the beach was a designated nudist beach.
Karen showed Mark around the city before heading over to the barracks and, with my pass, parked near the back gate and the beach. We walked down, found a place away from the crowd, and laid our towels on the hot sand. Karen removed her summer dress and was wearing a white bikini underneath. I stripped off my shirt and ran into the ocean.
We swam around and chatted in the cool water before returning to the towels and sunbathing. I leaned over and untied Karen's bikini top, who was sitting between us. Reminding her this was a nudist beach. Mark was taken aback but laughed. He always wanted to see Karen nude and would try and sneak and peek when he visited her at home.
He recalled one day he came to visit, and he stood at her window and watched her change. Karen laughed and pulled her bikini bottoms to one side, and flashed her trimmed pussy. I then suggested that we get naked and remove the swimmers. As she sat there, I could see Mark had his eyes glued to her pussy. Karen was aroused by her swollen clit and labia, along with the tiny dribble of her juices leaking from her.