Let's call my girlfriend Kara \[F19\], and her sister, Chloe \[F22\].
So earlier today, we were joking around and she called me by my first name. This caught me off guard, because she usually calls me "babe" or "daddy" or whatever else, just not my name. For some reason, it sounded exactly like her sister and reminded me of her, so I told her - "You shouldn't do that, it reminds me of your sister." with a chuckle. She already knows I find her sister hot, and it does not take a genius to guess that I have fantasized about fucking her sister many times.
Fast forward to later in the afternoon, and Kara and I started making out on the couch. I had been edging myself for the last week so I was beyond horny and I started rubbing her pussy through her pants while we kissed. All of a sudden she stopped and in the most realistic way pushed me away a bit and said "MalevolentMonster, stop! What are you doing?!"
I almost passed out from the amount of blood that rushed away from my brain and into my cock. She KNEW that saying my name like that would make me think of her sister. Was she really doing what I thought she was doing? All I could do was mumble "Fuck." as I went back to making out with her and playing with her pussy. At this point my cock was throbbing against her body.
Then she fucking did it again. "MalevolentMonster, we shouldn't do this! What if Kara finds out?!" That was it. She was pretending to be her sister, Chloe. I felt like the Gods of sex had blessed me with the rarest of opportunities. I still could not believe it, so I literally said "No fucking way. Shut the fuck up." and she just took my hand and slipped it down her pants, onto her bare pussy... and I lost it.
My brain went into overdrive as I started imagining myself rubbing Chloe's pussy and started making out with her. We both became kinda aggressive and animalistic, because it felt like we were friends having sex for the first time. Her pussy started getting dripping wet and my fingers were treating it like it was my bitch. I slipped two fingers in her right away and started fingering her hard while I leaned in and whispered in her ear "You have no idea how long I've wanted to do this to you, Chloe."
She started moaning and squirming under me, it was so fucking hot. She tried to "stop" me again between her moans, but I just started ripping her clothes off saying "This will be our little secret, Kara will never know."
She was dripping wet. I slid my cock in while big spooning her and immediately started pounding her. I could not hold back. And she kept moaning my name over and over again, and it felt EXACTLY like I was fucking her sister, especially with her head turned away from me. I almost came within the first few minutes, but I pulled out and dragged her to the bedroom, and pushed her down into doggy.
Gripped her tiny waist and fucked her hard from behind saying all sorts of things like "You're such a good fucking girl, Chloe" , "You get just as wet as your sister, Kara" , "You sisters just love sharing cock, huh?". God it was so fucking hot. At one point she turned her head toward me and moaned "Is this how you fuck my little sister?" and I almost lost it again.
I switched her into missionary and started fucking her slow and hard while I scanned her entire face and body and imagined every physical similarity I could with her sister. I was verbally comparing her to her sister and she started playing with her clit. At some point I said "Careful Chloe, you might push me over the edge and I know you're not on birth control" and this just pushed her over the edge. She said "Fuck I'm going to cum." and there was nothing I could do to hold back anymore. I came violently hard inside her pussy as it squeezed my cock through her own orgasm and collapsed on top of her.
It was almost a little awkward when we looked at each other and just said "Wow."
She later told me that what turned her on the most was her seeing how turned on I was getting to the idea of fucking her sister. I am a lucky fucking man.