Susan stood quietly in the doorway for a moment, feeling a slight moistening between her thighs.Andy must have heard the familiar rustle of nylon tigh...s being pushed aside and looked up: “Hi Mom – have you met my maths tutor Bindi? We all call her Bendy at school, because she’s so flexible – you should see her in the gym in her leotard – all bare buttocks and long legs”Now Bindi was on her knees between Andy’s feet, having pulled off his jeans and hers. Bindi was sucking on her step-son’s rock. ” With that he gave my nipple a tweak. I could feel my cunt tighten as if an electrical current ran from my nipple to some hidden place down there. Why had Joe, my husband, never had that effect on me? Our sex life had been okay but we were not obsessed with sex. Lately it had almost become a perfunctory like an old married couple doing their duty to one another on a Saturday night. Of course we both traveled a lot and were under a lot of stress, so that was to be expected with the children. She kept moaning hard as I didn't stop my slow fucking and soon another wave of orgasm hit her and jerked her body hard. This caused my cock to plop out of her and she fell on me and lay there. She was feeling and rubbing my chest and sides as she whimpered with her first multiple orgasm.I let Dee lay on me for a while as she caught her breath. Finally, she slowly pushed away and sat up straight on my tummy, with her knees still spread. Dee looked at me and smiled as she shifted lower and now. I wiped her tear way and cupped her face. She reached up and planted a soft sweet kiss on my lips. I wanted to stop I really did, but I deep down I wanted my little sister more than anything!We kissed more with passion and I found my hands wandering her little body, exploring every curve she had. Her buttocks felt so firm. I heard her gasp when I gently squeezed them almost not being able to control myself."Oh Crystal is one lucky girl to have a guy like you kissing her like this and touching.