It was quiet and casual but nice. I'd ease my hand real slowly over towards him, and he'd slip his hand over towards mine. We'd inch towards each othe... for a minute then maybe the ends of our little fingers would touch lightly; just enough to feel.We'd stay that way for several minutes, intently listening to the teacher and apparently being absorbed in the lesson. But at least on my part, it was only about half on what the teacher was saying.It felt really comfortable, as if we were old friends. I’d always assumed that my sister was a ‘good girl’ not going any further than holding hands and kissing, now it seemed, I was wrong.I’d never seen a condom before out of the packet, so out of curiosity I took two from the drawer, along with a pair of sexy underwear and put the rest back on top, hiding the rest of the condoms. I slid the drawer shut and looked around the room, nothing else looked suspicious so I walked towards the door and pulled it closed. I checked nobody was in the corridor. There were about a dozen of us sitting around roughly in a circle, just chatting and putting the world to rights.Mary sat down next to me, and leaned against me, and eventually grabbed my hand, but she had already told me she wasn't interested in disappearing for some sex with someone she'd just met, so I was behaving myself, and just held her hand.Mike came into the room at some stage, and said that he was completely exhausted and was going to bed, and would we like some blankets? He had a. She immediately started to stroke him and, in no time at all, had his cock all the way in her mouth. I reached down and started to rub his balls while she was sucking him off. She pulled his cock out of her mouth and shoved it in my mouth. We were both taking turns sucking his cock. She stood up and took off her shorts and panties. I had her turn around and put her ass against the hole. I could feel his hands running all over her pussy lips, rubbing her clit, and fingering her pussy. She.