Flashback: Sarah's threesome with Amy and Carl

Sarah got lost in the thought of having her own cock, and how she had developed that fantasy:

Sarah and Amy had been lovers for years, ever since they tried practicing kissing with each other. Over the years, they had progressed to steamy, regular sex. Both girls enjoyed dominating the other, escalating until one girl folded and got her cunt or ass reamed out by the other and one of their strap-ons.
The girl's weren't exclusively gay either. On two occasions they had invited a member of the football team to share between them. Each girl had enjoyed the experience, but they wanted an opportunity to dominate a boy.
That opportunity had come about one month before, when Amy's cousin, Carl, had visited. Amy and Carl had fooled-around in the past, but it had never progressed to real fucking. Amy had of course filled Sarah in on the details, including Carl's talented tongue-work on her clit and the extra-large load of cum he shot onto her face from his nine-inch tool. One look at the older hunk, and Sarah begged her best-friend/lover for permission to seduce him. Amy gave her permission, with the condition that she could watch. The plan worked, until Carl refused to fuck Sarah unless he could also have his cousin. The boy had always been able to push Amy to her limits, and this time was no different. Both girl's enjoyed his expert fucking that night.
It was after Carl's cock was spent from blowing two loads in each girl, that he admitted to being bi. Since arriving at college, Carl had discovered the joy of man-sex. With his endowment, he was very popular with girls and bottom boys, but Carl had found some guys were scared of taking him and wanted to fuck Carl instead. While hesitant at first, he quickly became an expert bottom. When the girls found out about this, they immediately asked if they could fuck him with their strap-ons.
Amy went first. She planted her big black ten-incher at her cousin's entrance and shoved in. Sarah played with her clit while she watched the two. Amy became more and more aggressive and Carl became more submissive. She slammed into his ass and ordered him to take it like a good little bitch. Sarah came several times, before Amy came and collapsed with her fake cock slipping from Carl's ass. Sarah pounced on her lover and began 69ing her. A fully rejuvenated Carl then took his hard tool and slid it into Sarah's upturned ass.
In the month since Sarah lost her anal virginity, the girls had talked about pegging more guys, and even fantasized about having real cocks.