Her skin was glowing from the sun the day before, but the shadows under her eyes confirmed her lack of sleep the previous night. She hadn't woken up i... her own bed and had had to sneak back to her hotel room in the early morning. Embarrassingly, she hadn't been able to find her bra. This was normally not a problem but her lacy top was completely see-through. The elderly couple she had shared her lift with on the way to her room had been polite though. The gentleman had simply wished her breasts. I respond back with my hungry horny look "bedroom eyes, big smile and licking my lips". We quickly had small talk till the light turned green. She said that she was on the way to Galveston Beach for a long weekend and invited me to meet up with her. I had time to kill and told her I would meet up with her later that night. She gave me the address to a beach bar she would be at.I met up with her at the beach bar. She was with her two older sisters who were BBW also. But not as sexy as she was.. As far as I was concerned, our sex life was fine. We had been married for four years, so we had stopped swinging from chandeliers, but we had sex most weeks, usually on a Saturday, after we had been out with friends, for a nice meal. I wasn’t averse to ‘going South’ and Linzi, after some coaxing, had developed a liking for sucking me (but only as foreplay). I knew, exactly, how to make her come; so why would she have the need to look elsewhere? And who with?‘Knock-knock’. I nearly jumped out of. Different. My sister's vagina was so warm, wet, and tight, and because of that I almost cummed right away. But I managed to hold it in and slowly started to fuck my sister, pushing my cock into her deeper and deeper every time until it was buried to the hilt. Her juice was all over my dick her amazing smell reached my nose, making me fuck her faster. My sister was moaning with pleasure, and I reached up and grabbed her tits, and played with her nipple, which caused my sister to moan even.