...I certainly shouldn't have seen those," she finished pointing at the two hard cocks of her brothers.
"Aww please Kim," begged Tim as he moved closer to the bed, his cock pointing right at her like a compass needle to true north. "my thing is so hard it hurts!"
Kim considered him and his hard cock for a few seconds. I shouldn't even be thinking about this, thought Kim, but it's not like I am a virgin anymore and it doesn't seem fair to let Jim do it and not Tim. It's incest said her inner voice. Yes, but I already committed incest once, so is twice any worse she replied. Also, it had felt rather good to have a cock inside her, much better even than masturbating. Kim made up her mind and dropped the pillow. "Ok, you can do me too," she said and laid back on the bed with her legs open.
"Hicka bicka boo," said Tim pulling off his pyjames and scrambling up on the bed and between Kim's spread legs. Then he paused. "Er, what do I do?"
Kim sighed and reached down to frame her pussy with her hands. "Put your cock in here," she instructed him. "Since you weren't paying attention in Health, it is called a vagina or if you are vulgar like Bonnie, it is called a pussy or cunt. Your thing is called a penis or again if you are Bonnie, it is called a dick or a cock. When you have sex with a girl, your cock gets hard and you put it into a girl's pussy. That is called fucking."