"Anyone in there?" Jill said after knocking on the bathroom door.

"Be out in a second," I said. Actually, I didn't have to use the bathroom. But there was an eight-year-old's birthday party going on in the house and I needed a break from the noise.

I opened the door to let her in, and locked the door behind her.

"You hiding out?" she asked.

"In between baking a cake, cooking pizzas and popcorn, and the noise, I needed a quick timeout. This seemed like as good a place as any."

The party was for Scott, my now eight-year-old son. We invited about a dozen of his buddies over for the afternoon. Jill, age twenty-seven, was his sister and technically my step-daughter. But since she was already living on her own when her mom Anne and I met, I wasn't really a father figure in her life. I'm just the guy her mom married.

There was something about Jill that infatuated and aroused me to no end. She had long dark hair and sexy blue eyes. She was one of those top heavy girls -- she had slender legs, not much of an ass, but an amazing set of what must have been 38DD or larger tits.

I had often looked at her over the years and wondered what it would be like to have her in bed for a night, but dismissed as something that would just never happen. I never saw myself as someone who would fuck his wife's daughter. At Christmas, I gave Jill a hug and kiss on the cheek as thanks for the present she bought me, and I could have been dreaming but it seemed like she held on to our embrace a little longer than usual. Later, when we found each other under the mistletoe, we shared a long kiss on the lips. She must have felt the sudden growth in my pants, but never mentioned it.

She was back here at the house for New Year's Eve. Her boyfriend wasn't around for some reason. A few minutes after midnight, and when her mom was out of the room, we kissed. An intense kiss. And I knew she could feel I was getting aroused because she rubbed my hard-on through my pants. I grabbed her hips and we rubbed against each other for about thirty seconds before we heard Anne coming back. My wife and I had great sex later, but it was Jill that I was thinking of every time I thrust into my wife.

Thinking back on all of that, I smiled a devilish smile at Jill and gave her a very overt looking over. She was wearing a very tight-fitting long sleeve t-shirt and pants so tight they may as well have been painted on. Lust was on my mind suddenly and without saying a word I pulled Jill tightly to me and gave her a long, powerful kiss.

"Mmmmmm, nice," she said in obvious enjoyment. "But Mom is here and my boyfriend is ..."

I never heard what she was trying to say because my lips smothered hers again and our tongues started playing with each other. I wanted to feel all of this babe in my arms, and my hands started franticly pawing at her boobs and groping her ass, and pulling her against my hard-on.

"Nice cock," she said, reaching between us.

"Nice tits," I replied as I pulled up her shirt, pulled out one of her boobs, and started licking and sucking on her hardened nipple.

"Oh my god you taste delicious."

As I sucked on that nipple, I managed to unsnap and wriggle Jill's pants down past her hips and start to rub her moist mound through her panties.

"Fuck yes, rub my clit."

With my lips wrapped around a nipple and my hand rubbing between her legs, Jill and I suddenly froze when we heard a knock at the door.

"Is someone in there? I gotta pee," some boy's voice said.

"Sorry," I said while still rubbing. "You'll have to use the one upstairs. I'm fixing this one.

We probably should have stopped there, but Jill and I were both too damn horny. If this were any other time, I would have loved to spend hours stripping her down and licking and kissing her all over her sexy body. Not this time.

I pulled Jill's pants all the way down and turned her around so she could lean on the sink.

"Stick your ass out for me, baby."

"Give me your cock now," she demanded.

She was so wet no extra lubrication was needed. I slid my cock first between her legs, then between her ass cheeks, before pushing the head into her perfect pussy.

I pushed in slowly until I was all the way inside her and stayed motionless for a moment to feel her pussy muscle cling to me. I backed out slowly, and then back into her a little faster and faster, and faster still.

I could see Jill's knuckles turn white as she gripped onto the edge of the countertop.

"Fuck yes, make me cum, I'm gonna cum." And she did. Her hips bucked and she let out a suppressed cry of ecstasy as her orgasm overwhelmed her. Had there been no one else around, I'm sure that scream of pleasure would have woken the dead.

And when she came, I came. My balls exploded and my cum shot into her pussy. I hadn't cum so hard in such a long time, the thrill of fucking this woman with so many others so close by.

I hated having to pull out of her, but we had already been gone for seemingly a long time.

"You are un-fucking-believable," I said.

"I'm gonna love my next visit, I'm sure," Jill said.

I had just zipped up my pants and Jill had gotten herself back together when there was another knock on the door. This time it was my wife. "Hun, are you in there? It's time to cut the cake."

"Yes dear, be right out."

"Ok. Have you seen Jill? I can't seem to find her."

I looked at her, we smiled, and I gave her one more kiss. "Oh, I'm sure she'll come back wherever she is."