"Don't move bitch!" He ordered. And now it was Rachel's turn to get a strip tease. Vinnie ripped off his jacket and shirt to give Rachel a sight of hi... perfect body. She just wanted to reach out and run her hands over his dark skin. His perfect six pack, his pecs that he could bounce at will. And his arms...How much she wanted to be gripped in those arms, to be held close to this perfect specimen of a man and have him embrace her and then feel his tongue on her nipples again. The thoughts made. Then I realised it.Heard the shaky whisper of her voice.A voice, almost drowning in the roaring sea of thunder.My shaft, almost painfully surrounded by a tight wetness.“Sarah! What are you doing!” I yelled. I did grab her arms, but my grip was shaky. I couldn’t believe it. I never would have thought that she would be going this far.I was getting my first fuck by my big sister.My grab, as weak as a child’s. “Mmmmh,” moaned Sarah. “Mmmmh, Lars, Lars...”. It were the same moans I have heard for. The project was difficult and ambitious. Estrus is a very complex phenomenon that involves virtually all the major physiological systems. It is triggered by not one but several interacting biological clocks. It affects the endocrine system, releasing a flood of hormones which act as messengers to the brain, internal organs, and reproductive system. These in turn effect changes of their own. There are further influences from the external environment -- for example, the course of estrus varies. I excused myself to the bathroom and where he came into the play.I stood from a far distance and observed her behaviour. He must have asked for a dance.They were on the floor his hands were on her hips.She closed her eyes. He pulled to the corner and smooched her. She opened her eyes in shock and slapped him.She stormed away towards the crowd and I caught her just in time.She said she was tired and wanted to go homeFrom the corner of my eye I saw him standing away.His eyes looked quite angry.