As our kiss broke my cock now fully erect was sliding between her ass cheeks with just our bathing suits separating us. My hands found her breasts and...sliding them up under her bikini top I held them in my hands as I used my fore fingers and thumbs to gently squeeze her hard nipples. This was so taboo. Not only were we both married but our k**s were just in the other room at any moment they could come down the stairs and catch us. But our lust had taken over. I kissed my way down her spine to. Our parents went away for the weekend on a with two of their friends leaving the thursday afternoon, leaving my sister and I alone at home till the Sunday. The Thursday evening my sister and I while having dinner discussed what our plans where for the weekend. She was going to be out with her boyfriend as well as at home and I told her that I would love it if my girlfriend Cassi could come over on saturday so that her and I could have a bit of alone time.Suprisingly my sister agreed to. Mmmmm! I moaned softly as she began teasing it. Her fingers felt great on my labia and my pussy grew increasingly wet. But the more time went by, the more aroused I became and the more this teasing was starting to feel like torture. When I could finally bear it no longer, she stopped. I opened my mouth to protest, but only a powerful moan escaped. She had just buried face in my poon and her tongue was now darting in and out of me. Oh yes! I moaned. YES! Her tongue continued darting in and out. His friend was throwing him a party. Jim showed up too. When he arrived Jim gave him a "brohug" and whispered in his ear.''I'll give you your present later."Later after the party broke up, Sean and Jim left together. They were both going the same way. They went down a dark alley. Jim pushed Sean against a wall and kissed him on the lips. He kissed him back. Jim lifted up Sean's shirt and kissed down his stomach. When he got to his belt he unbuckled it and pulled down Sean's jeans and boxers..