My adopted sister and I got along very well. She hit her mid-twenties and her husband seem to be losing interest in her, I however, thought she was getting sexier. I don't know what started to turn me on, but almost every time I went to visit her and her husband, I would get a hard-on. My wife even asked me on one occasion, why I was so hard? I didn't know. We acted like to siblings always arguing and beating on each other. I guess it was kinda kinky thinking of my sister and sex. One day she invited me to lunch near where we both worked. I thought it was unusual but I agreed. We met and it was nothing but a bitch session about work, her husband, her nosey female neighbor always trying to look in their bathroom at her naked. Wow! The got me turned on. Anyway, she seemed so flustered. I told her she needs to chill out and relax, maybe even have some good hard sex with Mark, her husband. Sally laughed and said he was good for a quick fuck but that was it. I laughed because that was the first I have ever heard of her sex life.
Seeming irritated Sally asked me, "What are you laughing about? Do you think you could make me have an orgasm?"
I was stunned. She never, ever asked me anything liked that. Then she smiled and said, "Got you, bro."
I didn't know what to say, when all of a sudden I said, "I bet I could make you have a multiple orgasm." What did I say?
She smiled, "Were not suppose to do that, we're bro and sis, remember?"
"Chicken!" I said not really knowing what I was saying.
She smiled, but it was a smile of disappointment, like she wanted to but with both of us married, we shouldn't be doing that, let alone, being brother and sister.
It was getting late and I had to go back to work so I said, "I got to go, but if you want to take me up on that bet, I'll be home for lunch tomorrow at 12:30, be there and you'll have your multiple orgasm." I left her sitting there and went back to work. My dick was so hard the whole day that it hurt. I felt so guilty about what I said and hoped that she didn't show for lunch and it would all be forgotten.
As I arrived home for lunch the next day, I was relieved that she was not there. But as I got to the door, she beeped her horn and pulled in. I was stunned and I could see she was too. She hopped up to me and said, "So, you ready for the bet, bro?"
All I could say was sure.