The next day Jennie's ass was very sore. She complained to me, and had no desire for anal sex, but not so was the case for me, for it was all I could think about. She would refuse my advances while at the same time tease me by posing seductively in her skimpy nightie. When I could not stand it any more I would grab one of her butt cheeks and she would say, "Nooo, it still hurts from yesterday." So we would both try to get caught up on the homework we had been neglecting while preoccupied with sex, until she would tease me again.

Eventually Mom came home and I had some relief from the mental torture, but I still could not stop thinking about doing Jennie's ass. In bed at night I could not sleep and began to masturbate, thinking about her. Finally, I couldn't stand it any longer, so I quietly went to her bedroom. Jennie was lying on her tummy, asleep. I pulled down the blankets and lifted her nightie, revealing her nice little ass in the moonlight that was streaming through the window. I reached down under her mattress and took out the KY, where she had it hidden. I applied some to my middle finger and gently pushed it against her asshole. If Jennie wasn't awake before, she was now.

"Uh, what're you doing?"

"Quiet, you'll wake Mom," I cautioned. "I thought if I rubbed it for you it might make it feel better." I lied. We both knew what I wanted. "Does that make it feel better?"

"Umm, kinda, it's still a little sore." With that signal to proceed, I began to slowly push my finger in, still being careful not to cause her too much discomfort or pain so that she would not refuse my further advances.

"How's that?" I asked, my cock responding to the sight and feel of her tight little ass clenching my finger.

"It feels better." She opened her legs wider and pushed her butt up.

I pushed my finger deeper. "That still feel better?"

"Yea, it feels good." I slowly pushed my finger all the way in, twisting it around to massage her colon. In the dim light I could see by her expression that she was lost in the sensation of my finger massaging her asstube. "Mmm yea, feels a lot better. Keep doing it."

My cock was pushing so hard against my underwear it hurt. I wanted to remove them, so I slowly withdrew my finger from Jennie's butt. She turned her head to look at me, "Hey, what are you doing. Why did you stop? I said it feels better."

"I just want to take my underwear off, " I assured her, "and don't talk so loud or you'll wake mom". Seeing how much she wanted me in her ass made me want to fuck here there again that much more. When I pulled my underwear off my cock sprang out rock hard.

Jennie's eyes were glued on my throbbing cock. "Wow, your penis must really like my butt a lot."

"Yea, it loves your butt." Truer words were never spoken.

"And my butt loves your penis! Don't forget to put KY on it!"

I had intended to continue massaging her colon with my finger, but now it seemed she would rather that I massage it with my dick. I dutifully applied KY to my member, almost shaking in anticipation, and then climbed atop her as she arched her butt further up to meet my cock. As I rubbed my cockhead in her open crack she wiggled her butt just a little, until it settled against her anal ring. I pushed gently at first, and then a little harder, then my cock slipped in more easily this time. Her ass was learning to adapt. Wanting to be gentle and not hurt her, I held my cock still just inside the opening.

After a few seconds Jennie bent her knees and softly kicked her heels against my backside, causing her sphincter muscles to clench my cock. She wanted me to push it in some more. I slid it in slowly but steadily until it was a bit more than half way, pausing then to see her reaction. Her eyes opened and she glanced at me.

"It feels good. Keep going." With that, I pulled back a couple inches and drove in deeper. With each thrust I instinctively increased the tempo. Jennie held her butt still, allowing me an easy target to keep ramming my cock into. Just then I heard Mom cough, then get out of bed. We both held perfectly still, my cock still deep in Jennie's ass, while Mom went to the kitchen for a drink of water. It seemed like hours, but after a couple minutes we could hear her go back to bed.

I slowly began fucking Jennie's ass again, being very careful not to let the bed squeak. Jennie's ass was now very relaxed, taking my cock with no problem. She looked so content, thoroughly enjoying her internal anal massage, as I slowly but steadily pushed it in. Reflexively, I began to fuck her harder. The bed began to squeak, but I didn't care. Suddenly my cock spewed several jets of cum deep into her ass.

"Jennie, that was awesome!" I whispered breathlessly, "it felt so good!"

She smiled. "See, I told you anal sex would be fun, didn't I? Now you better go back to bed."

She was right. I slowly withdrew my cock, not wanting to be too abrupt like the last time when we made a mess on the bed. My cock was half hard when it popped out, still dripping cum. Jennie turned around and sat up eyeing it. She kissed my cockhead.

"Good night, Mister Wienie, and thank you. You're so cute! Now go to sleepie. I have to go to the bathroom now." With that she abruptly climbed out of bed and walked rather hurriedly to the bathroom. My crazy sister had been talking to my cock. Not waiting for her to return, I retrieved my underwear and went straight to bed, quickly falling asleep, already anticipating our next anal adventure.