Of course we did a lot of touching and grab assing and even some kissing. When Tammy started grinding her pussy against my thigh, I said it was time w... laid on the blanket for a while.Becky and I laid on either side of Tammy. Tammy was sharing kisses with me, and with Becky. I started caressing her breasts as she and Becky were kissing. Tammy was moaning as I let my hand trail down her body and cup her very wet pussy. I noticed Becky had a hand on one of Tammy's breasts. My cock was an iron. Finally, he lowered his head to one breast. I moaned as he teased my nipple with his teeth, careful not to touch it with his tongue.After giving anyone who happened to be at their window the chance to view my vulnerability, he pulled me up and led me to the elevator. In the elevator, he removed my panties, letting the palm of his hand graze against my swollen sex. I ground my clit into his palm, wanting him to do something, anything, but resisting the instinct to be so brazenly demanding.He. My body froze up and I looked down. What I saw was my hard cock, standing straight up towards my face and my sisters smiling, giggling face right next to it, singing "Babbbbby brotherrrrrr..." while her fingertips gently and slowly moved up and down... up and down on my hard cock. I looked over at her ass, trying to take my mind off of what was happening. She stuck her butt up in the air."Grab my butt," she whispered, and she smacked her butt.My left hand shot out and I grabbed onto Tara's butt. I asked her what she was going to do, she asked me if I would let her or want her to call them and organize a meeting saying that she would abide by my decision. In the end she decided not to call him but kept his note.The following Monday Joan called me at the office and told me she had to stay back an hour every day for the next week as the company she worked for landed a new high flying client. Joan would arrive home an hour later than usual all week, there was nothing out of the ordinary.