My wife Karen has a sister, Kris, who is seven years younger than she is. Karen and Kris have always been close, even with the difference in their ages. When Karen and I got married, Kris (who was 15 at the time) was one of the bridesmaids.
Once, when Karen and I were still pretty newly-married, we had Kris, who had just turned 18 at the time, come and stay with us for a couple weeks in the summer, so we could show her around the sights of the 'big city' where we live (truthfully, our city isn't all that big, but the town where Karen and Kris grew up is pretty small, so to them it feels pretty big), and get her out of her parents' hair (and vice versa) for a couple weeks. For the visit, we put Kris up in one of our spare bedrooms, which, like all of the bedrooms in that house, was on the second floor.
One Friday afternoon during Kris' visit, I left work early, and showed up unannounced at the house. Karen was pleasantly surprised to see me, and started making plans to have a picnic supper at the beach. I hopped up the stairs to change out of my 'work clothes', and into something more suitable for picnicking at the beach.
I got to the top of the stairs, and spun to head down the hall to my bedroom. As I did, the door to Kris' room was open, and Kris was standing there, completely naked, checking herself out in the full-length mirror in her room. She didn't immediately notice me, so I had a few seconds to appreciate her nakedness. For an 18-year-old, she had surprisingly full breasts, tipped with puffy pink nipples. Her waist was long and slender, similar to Karen's, but maybe even more slender. She had nicely rounded hips, and a lovely tuft of light brown pubic hair. I couldn't help smiling; my wife is a very beautiful woman, and her sister obviously came from the same gene pool.
I was only able to enjoy my gaze of Kris' nakedness for a short time before she noticed me. When she did, she simply stood, dumb-struck and stared back at me, without making any kind of move to cover herself. I walked over to the door, and without saying a word, closed it.
I continued on to my room, and changed my clothes for the picnic, as I'd set out to do in the first place. Then I headed back downstairs. I snuggled up behind Karen, kissed her and playfully fondled her breasts.
"Mmmmmm," she purred. "Feeling a little frisky, are we?"
"Well, I just got an eyeful of your little sister naked."
"You what?!?"
"When I went upstairs, she, uh, apparently didn't think she needed to close the door in the middle of a Friday afternoon. . ."
Karen burst out laughing. "Then she gets what she deserves!"
I was relieved that my wife saw the humor in the situation, and didn't ascribe any 'nastier' motives to my enjoyment of her sister's inadvertent little peep-show. In a few minutes, Kris came downstairs, still blushing.
"I hear you've been flashing my husband," Karen said, smirking.
Kris turned deep red. "Oh, Karen, I'm sorry! It was totally an accident!"
Karen laughed. "I know; I'm just teasing you. No harm, no foul."
We went ahead and had a great time on our picnic, and nothing further was said about the 'incident'. Although it was a couple days before Kris could look me in the eye again.
*****
In the fullness of years, Kris got married, and Karen stood up at her wedding. Her husband turned out to be a jerk, though, and after a couple years, they got divorced. Kris was 25, had no job, and no place to live, so Karen and I offered to have her move in with us, and she gratefully took us up on our offer. It worked out well, as far as we were concerned. Kris had her own room, and we tried to give her as much privacy as we could, but still let her be a part of our family as much as she wanted to be. After the first month or two, most of the adjustments had been pretty much smoothed over, and the three of us settled into a comfortable arrangement, even though I knew that living in her sister's house was not Kris' preferred living arrangement.
Being newly single again brought a whole set of other adjustments for Kris, as well. One weekend, I was putzing around the house, doing little projects, while Karen and Kris shared some coffee over the kitchen table. I wasn't trying to listen in on them, but I couldn't really help it.
"I'm telling you," Kris began, "I haven't had sex in so long, my poor pussy is hungry to have a cock inside her. I'm about ready to jump anything with a penis. But honestly, the idea of screwing some guy I barely know just creeps me out, so I don't know what I'm gonna do." She laughed, and continued, "You should probably keep close track of Ben. I'm pretty sure he's got a penis, we know each other really well, and I live right here in the same house with him."
"Yeah," Karen replied. "And he's already seen you naked! But at least it would be all in the family!"
I felt blood flowing to my face, and also to another part of my anatomy, a couple feet lower. I thought it best to busy myself in another part of the house as my wife and her sister broke out in gales of bawdy laughter.
*****
A couple weeks later, the three of us were unwinding together on a Friday evening, after a busy week. I brought out a bottle of wine, and before long, all three of us were thoroughly loose and relaxed. As the wine flowed, the conversation became increasingly sexual as our inhibitions slipped away. At one point, Karen, who was well into her wine by then, turned to her sister, and said, "You might not know it, Kris, but Ben is a great pussy-licker!"
I did a double-take at my wife's tipsy revelation of my sexual talents. It was true, I did take pride in my cunnilingual skills, I just never expected it to become a topic of conversation beyond the two of us.
"Really?" Kris responded.
"Oh, hell, yeah!" Karen answered. "He can make me come over and over and over! And not only that, but his cock is reeeaaal nice, and he lasts a loooonnnggg time."
Kris looked at me. "Is that so?" she mused. I grinned and shrugged my shoulders, trying to play along, without seeming too pushy. "I just might have to sample his talents sometime. . ."
"You just might," responded my wife. And both women broke out in uproarious laughter.
This was starting to get pretty raunchy, and I thought I should excuse myself, and leave the women to their revelry. It wasn't that I didn't want to fuck Kris, but I figured the initiative for anything like that should come from the women, and specifically my wife. Karen was certainly feeling randy enough that I expected some hot sex at some point that night, at any rate. I went to my room and hopped into bed, figuring I could get some sleep before Karen came to bed; she certainly didn't seem like she'd be winding down anytime soon.