I have recently come to have an insatiable desire for my girlfriends sister. She is the younger sister and I just can't stop thinking about her. Whereas my girlfriend is beautiful, her sister is smokin' hot. She dresses sexier, does her hair sexier, and has more sexual confidence (so far as I can tell). She is also a volleyball player, and has a lot better body than my girlfriend.

The thing is, she is young enough that I never would have considered her... It just wouldn't seem right. I love my girlfriend, and haven't even thought of anyone else... but her sister is all of a sudden the only person I EVER think of. Probably cause my gf is very strict about sexual things, and doesn't do much beyond a standard missionary position, and doesn't really dress "sexy" even though she is good looking.

Its also kind of exciting to think about, because while her sister IS a virgin, she has no problems with oral sex, and does it all the time.

My fantasy is that while hot-tubbing one night (a normal affair for the three of us) we will just "happen" to drink a little to much. Of course, my gf loosens up for once, and we start fucking while I make out with her sister. After giving her an orgasm, we decide to switch positions. While switching positions her sister takes my cock into her mouth and starts sucking me off, and my girlfiend is too caught up in the pleasure/alcohol to care anymore whether our sex involves her sister.

After a few minutes of this, I start having sex with my gf again doggy style position over the edge of the hot tub. She cums fast, and easily, and within a few minutes is screaming with another orgasm. This time, I get to fondle her sisters breast and start playing with her pussy too. After a few minutes I can't take it anymore, and pull out of my gf so that I can attack her sister.

We fuck for several minutes before I decide that I need her mouth around my cock again, so I pull out of her and go stand over her so she can sit up and suck me. She procedes to give me the best head I've ever gotten, and is excellent at deepthroating my 8 inch cock. Then I flip her over and take her from behind, and start to kiss my gf again while she is sitting next to us. In my heightened arousal, I announce that I am about to cum, and to my surprise my gf's amazingly hot sister turns around, takes me into her mouth, and swallows everything.

This of course, turns into a regular event ;)