I used to work with a man who related the following experience to me. Knowing the people as well as I do, I have no doubt that it is true.
He was married to this woman who had a step-daughter. She was one hot girl. She had a body to kill for and loved to show it off. She would come to the office to see her step-dad and would be wearing skimpy little tight shorts with a thin top that was low cut. Most of her tits would be showing and she never had on a bra. Her hard nipples would always be poking through the thin marerial. The tops she wore were always cut off at the bottom and her hot flat belly would be in plain view. Even though she was a pretty girl I always thought she dressed kind of slutty.
She was nineteen when he told me that she had been hitting on him a lot. One night he told his wife that her daughter acted like she wanted to go to bed with him. In the course of the conversation his wife made a bet with him. She bet him that he could not get her in bed with him. He said, 'You really want me to try and see if I can play around with your daughter?' His wife told him to go ahead and try it because she did not believe the girl would do anything.
A few days later he came home and his step-daughter was there but told him her mom had gone out shopping. She started teasing her step-dad and before you know it he was in bed with her. They started playing around with each other and kissing. Pretty soon they were both naked. He said her young body looked even better than he thought once he saw her naked. He started fingering her pussy and said it was soaking wet. He gave her a couple of orgasms with his fingers before she took hold of his cock and started running her hand up and down the shaft. She jacked him slowly until precum was leaking from his cock. He said she had another orgasm and about the time he popped his nuts the bedroom closet door opened and out stepped his wife. His wife quickly pulled off her clothes and got in bed with her husband and daughter. He said his wife's pussy was soaking wet. He said he had never seen his wife so hot and horny. Both he and the daughter proceeded to play her. He said while he was fingering his wife's pussy her daughter was sucking her mom's nipples. He got his wife off several times with his hand. He said he had to use his fingers because his dick was shot.
He told me that after it was over his wife got mad as hell for him fooling around with her daughter. It seems that she had also made a bet with her daughter that she could not get her step-dad in bed. He wanted to know what I thought about it. I said, 'Well hell, she asked for it. She shouldn't have made a bet with you or her daughter in the first place.'
Anyway, apparently they got things straight because they are still together. Eventually his step-daughter married and moved out, but he got to enjoy them both for a couple of years.