Suddenly, you remember you were planning to go and surprise Sally this weekend. Her parents, both very important businesspeople, are both out on work trips for the next few days, so you decided it would be a good opportunity to see if she wanted to... "hang out". But if you're gonna go try to get intimate, you might want to get a shower first.
You head back into the bathroom and strip down, getting the water started in the shower. As you pull down your underwear, you can't help but notice yourself in the mirror; you don't have the most fantastic body by any standards, but for some reason your package looks particularly large today, and you're pretty sure that half chub from earlier has gone down by now. Normally your dick hangs flaccid around 3", but today it looks like 4-5"! You also become aware of the fact that your balls look and feel a bit heavier as well. You're not sure where this sudden growth spurt could've come from, but you're not gonna complain. It's just another surprise you could bring with you when you visit Sally.
You step under the warm water in the shower and grab the soap, lathering it up against your body. Aside from that strange exchange with your mom this morning, today seems like it'll turn out pretty well. You had a pretty pleasant dream, though you can't remember what it was, and now you'll get to spend the day banging your girlfriend with your mysteriously enhanced member. As you rub the soap over said appendage, you get curious about how big this thing can get now. Your old maximum size was 6", but who knows what it could be now?
You reach down and wrap your fingers around the soft meat, closing your eyes and imagining something to get you horny. In your mind, you see the bathroom door open, and in steps your girlfriend in her pajamas, a little surprised, but pleasantly so.
"Oh, Steven!" she says, her eyes widening upon seeing you. For some reason you're having a hard time imagining her normal British accent. "Sorry, I'm still half asleep, I didn't hear the water. But... oooh, what's going on down there...?" Normally you'd be embarrassed to be caught masturbating, but for your girlfriend you keep going, matching the seductive smile she's giving you. You look down and take a peek at your now throbbing erection to find it at a whopping 10"! Quite satisfied with this, you close your eyes and look up at daydream Sally again.
"You like it?" you ask, not realizing you've actually said this aloud. But who cares, everyone else is asleep right now, and the water would cover what you said.
"I do... Mind if I join you?" Before you even answer she already starts to take off her top, revealing those perfect breasts, untethered by a bra. You simply allow her to answer her own question by continuing to strip, removing her tiny pajama shorts, leaving her in just a frilly black and purple thong. Somewhere in the back of your mind, you think about how your sister Liz has one just like that. This too drops to the floor, and your imaginary girlfriend is now completely naked before you. She enters the shower with you, the hot water cascading down her curvy, pale body, fueling your erection further. That dream last night, whatever it was, got you really horny today; this fantasy is incredible.
"Wow... you're so big, Steven... I had no idea..." she whispers in your ear. You imagine it's her slowly stroking your dick instead of your own, her small hand barely able to wrap around it's girth. "Can I suck on it? Pretty please...?"
"If you think you can handle it," you whisper back. She giggles at your challenge, but eagerly accepts it. She kneels down in front of you, rubbing your wet rod all over her face, giving it a few teasing licks and a kiss on the fat tip. Even if it's just imaginary, it feels incredible; even more incredible is the feeling of it slipping into her warm, tight mouth, stroking the remaining length with both hands.
"You taste so yummy," she coos, licking up and down your length and trying to shove as much of it down her throat as she can. "Do you have anything else for me that tastes yummy...?"
"I will soon if you keep that up," you tell her, beginning to thrust your hips a bit. She keeps pace by bobbing her head and stroking faster, bringing you closer and closer. "Oh here it comes, baby!" you growl, pulling out of her mouth and aiming right for her face.
"Mmmm, gimme all your cum, big bro!" she moans, opening wide to accept your-- wait, "big bro"?!?!
You open your eyes just as you begin to climax, and realize that it is not your girlfriend kneeling before you, real or fake. It's your sister Liz!!! That's why she was wearing that thong, and didn't have her accent. It's too late to turn back now, though; your balls are drawn up and the eruption is about to begin. You moan in regretful pleasure as massive ropes of goo paint your little sister's face white. Her smooth face is covered in your baby badder, covering the light freckles sprinkled on her cheeks and nose white, and her brunette gets covered in your dick's white glaze. You try to aim away but she keeps your cum cannon pointed straight at her face, and in your state of pleasure you're in no place to overpower her. Fifteen, twenty, twenty-five, the number of spurts keeps climbing, setting your personal record for the biggest orgasm you've ever had; why did have to be a product of incest?
Finally, after thirty-two hot, creamy, and sinful shots of sperm, your orgasm slows to a dribble. Your sweet little sister looks like a doughnut that's been glazed as least five times more than normal. She gulps down the jizz that had been pooling in her open mouth, wipes your cream from her eyes, and looks up at you with a big gooey smile.
"Thank you, Steven," she says in a sultry voice. "That really was yummy."
"L-L-Liz, what the-- this is-- I thought-- you--" Able to speak once again, you stutter to find the words you mean to say. "I thought you were... you were my girlfriend... I was just..."
"I can be your girlfriend if you want me to..." she says slowly, standing up and wrapping an arm across your chest and over your shoulder, leaning in to kiss you. You immediately duck out of her grasp and bolt out of the shower, grabbing your towel and your clothes and booking it to your room as fast as possible, locking the door behind you.
"Awwwwwwwwww, Steven!" she moans. "What's wrong? Come out and play with me more. I can out on a British accent if you want me to." Her attempt at an English accent is forced and awkward, and is certainly not going to convince you to commit more incest with her.
"Liz, go away!" you yell at her through the door. "That was... that was an accident! We shouldn't have done that!"
"Maybe we shouldn't have done it... but it doesn't mean I don't want to do it again..."
"Well it does for me! I'm going to Sally's house, so just forget this ever happened!" You quickly dry yourself off and get dressed, ready to sprint out that door and go straight to Sally's house after this. You have an actual girlfriend you want to go have sex with; bukakkeing your sister is the last thing you want on your mind right now. As prepared as you can be, you head out into the hall to find Liz still waiting for you, wrapped in only a towel, a heavy layer of splooge still covering her face.
"Please? Just one quicky before you leave?" she begs, reaching for your crotch. You quickly bat her hand away.
"No, that was really, really inappropriate, and a complete accident. You can't tell anybody about this, okay?" She's persistent though, and keeps pestering you to let her just touch your dick. Why is she so obsessed with it? You eventually just have to ignore her and rush out the door before she can stop you. You hop on your bike and leave her, and hopefully the memory of that shower, in the dust.
Stop thinking about it, you tell yourself as you pedal down the street. It was an honest mistake. Plenty of guys probably end up having sex with their siblings while they're having fantasies, right? Right?! No, of course they fucking don't! You were a complete idiot! You let that get completely out of hand! You resolve from this point onward never to have sexual fantasies in the shower with your eyes closed again. Dreams and porn and actual sex with your girlfriend would be enough for you.
In the darkest reaches of your mind, though, you have to admit... Liz looked pretty sexy with your big cock stuffed between her lips. And all that jizz all over her face... No! Stop it! She's your fucking sister! You can't think of her like that!
During your internal battle, you fail to pay attention to what's in front of you and hit a large rock with your front tire, sending you flying! You're launched off your bike and crash to the ground, which luckily ends up being soft grass. You take a moment to get your bearings and wait out your dizziness to see where you are. Where did you crash?