I'd like to thank
Elenia26
for the assistance in editing and adding creativity to this piece of writing.
My wife's 20 yr old sister, Tina, had been staying with us for a while now. She'd graduated from college and was actively seeking a job. We'd told her she was welcome to stay with us until she found a stable job and accumulated some savings before moving out on her own.
Both I and my wife had full-time day jobs, her working longer hours than me. This meant that she had to leave a couple of hours earlier than me in the morning. Tina got up later than my wife, but before I left for work, and we usually had breakfast together.
A few days ago Tina walked into the bathroom to grab the toothpaste when I was about to take a shower. Since it was just my wife and me, we never locked the bathroom door. I was completely naked with no towel within my reach. My immediate reaction was to use my two hands to cover myself.
She froze and our eyes met for a long moment. I was painfully aware that this was my wife's twenty year old sister. In the second that we were both rooted to our spots, I was aware of the way her t-shirt fitted around her breasts, her long legs, and the way her eyes flitted to me and then away. Then she muttered something inaudible and quickly left with the toothpaste. It was only after she left that I realized the head of my cock and half of my sack were somewhat visible despite my attempts to hide them.
"Oh God, did she see that." It was the first thing that came to my mind.
Part of me wished she had, and like a little kid who wanted his wish come true my mind started to conjure the possible ways she might have managed to take a peek during that short time. As my thoughts escalated I started to picture Tina more vividly. I had just seen Tina with her t-shirt clinging to her body, her nipples poking out through the material as though they were screaming for attention. My mind went back to the few occasions where Tina had bent over in front of me and I caught a glimpse of her light brown nipples. Tina sports a pair of breasts that any woman would be proud of. They were neither huge nor tiny, and would bounce a little in a hypnotic manner when she'd walk fast. While she may wasn't slim as a runway model, she wasn't chubby either. She had a lovely figure that she worked hard to maintain. The only thing I've seen her complain about is her height. Standing at 5'3" she'd always prefer wearing heels on social outings. The nice thing about this was the way it accentuated her curves and brought out her ass. She might not have an ass to match her breasts but it did sway gracefully when she walked. Even with the heels I was taller than her, at 5'7", and stronger, too.
As I made my way out of the room all fully dressed I saw Tina sitting at the dining table. I took in all of her at once. Her dark brown hair with copper highlights falling onto her face. Her luscious lips smudged in milk from her cereal bowl. It reminded me of the times when she told me how her boyfriend back then mentioned how kissable her lips looked.
At breakfast we acted as though nothing happened. Tina didn't mention it, so I decided not to say anything. I also decided my wife didn't need to know, as I didn't want to make a big deal out of it.
The next morning, as I was about to step into the shower I saw the bathroom door creep open and there walked in Tina.
"I really need to buy my own toothpaste", she said, glancing in my direction out of the corner of her eye.
I grabbed for a towel and pulled it toward myself but in my haste I was a little clumsy and dropped it. I picked it up right away but in those 10 or 15 seconds Tina had picked up the toothpaste and turned towards me. I couldn't help but notice she looked directly at my crotch and only averted her eyes once I covered myself with the towel. She scurried away quickly.
Part of me found it thrilling to let my wife's youngest sister see my most private parts.
I stepped into under the shower and let it run. The water kept trickling down my body, and my mind kept wandering . I was certain that Tina had seen me in all my glory. Not only had she taken a peek, she had been staring at me. Her eyes were fixed on my cock, not taking her eyes off until I covered myself. Soon my cock started rising, pulsating in tune with my breathing. It dawned to me without any shred of doubt that I was lusting after my sister in law. I was having lewd images of my wife's youngest sister.
I closed my eyes and wrapped my fist around my cock. I started stroking myself, pushing out the thought that it was wrong to fantasize about my wife's sister. In my state of arousal I justified that I was only thinking about her and there was no harm in that.
As I kept stroking I could feel my cock grow to full mast, the whole length of it resting on my palms. I looked down and imagined Tina was on her knees, taking the swollen mushroom head in her mouth. The veins at the base of my cock were standing out visible. I kept stroking my cock from its base all the way to the head, imaging it disappear in her mouth. As I pulled back my tight fist around it I could see the swollen purple head re-emerge. I started to wonder if Tina would like to suck on it. Would she like the taste of my cock?