Mike sneaked a peek into the partly opened door of his big sister’s bedroom. The boy was just starting to get interested in girls, and lately had developed a habit of spying on his big sister. Judy at 19 years old was only 8 months older than Mike. In spite of their differences, Mike loved his big sister, and would have done almost anything for her.

Today, the boy was in luck. Judy had just returned from the shower, and was laying naked on her bed, reading. For several long minutes, Mike looked at his sister’s developing body, taking her in, from her lightly rounded ass, to the pert bumps that were, at the moment, pressed into the furry bedspread. Each time the girl shifted position, Mike would get a glimpse of another part of her delightful young body.

Soon, the boy’s cock was tenting the front of his shorts. Mike was wearing shorts, and not much else, as it was mid-summer, and 85 degrees outside.

For somewhat the same reasons, Judy was in no hurry to get dressed, and swelter in her clothes again.

After reading for about 15 minutes, during which time Mike was unable to draw himself away from the door, Judy started to get bored with the book she was reading, and turned over. As she did so, Mike was treated to a full frontal view of the girl’s pert young tits, and the light fuzz that topped her almost hairless little snatch. This unexpected delight, caused the boy to suck in his breath with a slight gasp.

Judy heard her brother’s intake of breath, but carefully acted as if she hadn’t noticed. Continuing her motion, the girl spread her legs, and lay on her back, giving the boy a complete view of her open little cunt, now starting to drool cream at the wondered of turning on her little brother. Ever since the girl had started having periods, she had been dreaming about putting on a show for a man, and possibly even getting fucked.

Her mother had explained to both the children when they were young, about how babies were made, so Judy knew what happened. It was scary, thinking of having a baby, even though it was also exciting. So Judy mainly dreamed, not daring to actually try anything.

Now, knowing her little brother was sneaking peeks at her naked body, turned her on. She had never wondered of her little brother before as a feasible sexual partner or boy-friend, but the kid shared her good-looks, was bright and friendly, and in general, was all that a girl could ask for.

Judy decided to try and ‘make-out’ with her brother. They couldn’t actually fuck, as she didn’t want to get pregnant, but there were lots of things two horny kids could do without actually fucking. Judy wondered it over, at all times carefully turning her body to give her little brother fresher and even more tantalizing glimpses of different parts of her developing young body.

How could she get Mike into her room, with both of them naked, without seeming like a slut? He was obviously interested, and from the shiny head of the oversized cock that was peeking out of the top of the little boy’s shorts, well equipped for the job.

A slight ache in her neck, as she tried to keep the boy in view, in the mirror, gave Judy the idea she had been searching for.

“OW!” said Judy.

“Aughh! Oh that Hurts!”

The girl twisted as if in pain, and lay face-down on the bed, trying to reach her back as if she were in agony.

Mike had been enjoying the show, when he saw his older sister seemingly strain her back, and collapse onto the bed. Worry about his sister being hurt, overcame his fear of being caught peeping.

“What’s the matter, Judy” he worriedly inquired.

“My back. It’s killing me. I think I got a cramp.”

Judy hammed it up for all she was worth.

“Shall I go and get Mom?”

Their mother was the last person Judy wanted to see at the door right now, maybe her handsome father but… Judy shut the wondered off with a snap.

“No. It’ll relax in a minute,” she explained.

“Maybe you could help by rubbing my back.” Judy carried on with her plan.

Tentatively, Mike approached his beautifully naked big sister. He was so excited, at the wondered of actually touching the girl’s naked skin, he didn’t notice the girl’s movements that belied her ‘cramp’.

“You mean like this?” he said, starting to massage the girl’s shoulders.

“Yes, but farther down” directed Judy.

Dutifully, Mike started massaging ‘farther down’, until he was rubbing the middle of the girl’s back.

“How’s that?” he inquired.

“Fine, but harder,” requested his sister.

Mike was already rubbing as hard as he could, the girl kept being pushed away, when he tried to do it harder. He explained this to his sister.

“Why don’t you get on top of me, and do it.” Judy almost snickered, as she realized how well her plan was working.

“Uh Judy,” warned Mike, “you’re naked, and I…”

How could he tell his innocent sister that he was sporting a hard-on for her.

“That’s OK. I don’t mind. Why don’t you take your shorts off too, if that’s what’s bothering you?”

Judy was so proud of herself for thinking up that line, she almost burst out laughing.

“But Judy, I’ve got a hard…”

He couldn’t say it.

“So you’ve got a hard-on. Big deal! Just don’t try to stick it in me. OK?”

Judy hid her face in the pillow, so her little brother couldn’t see her expression and spoil everything.

Mike couldn’t believe his luck. His big sister didn’t mind. Now he could get on top of her, and feel his big sister’s body all over, under the pretense of giving her a back-rub. It was almost too good to be true. Hurriedly slipping out of his shorts, Mike climbed on top of his sister, and started to rub her back.

Judy was pleasantly surprised. Mike was good! He pressed into the small of her back with his fingers, and began giving her a massage that threatened to put the girl to sleep. After working a while on her back, Mike began running his hands up and down Judy’s sides, and then he began rubbing her shoulders like an expert masseuse.

Judy didn’t know it, but she had picked the perfect thing. Mike had been learning to give his mother massages, under the direction of his father, because the man was unable to treat his wife to the long hard massages that she so loved, so he had started enlisting the aid of their son. Mike’s arms had been growing stronger, over the past few months, and he was getting to be very good at it.

Presently, Mike had somewhat of a ‘big’ issue. His cock was banging against his big sister’s cute little butt, and leaking clear slippery fluid down into the crack of the girl’s ass.

Judy enjoyed the feel of Mike’s cock sliding against her rounded little ass.

“Judy. My cock is getting in the way,” said Mike.

“Can I put it down between your legs for a minute?”

Mike held his breath, waiting for his big sister to answer.

“Well, OK. Just for a minute. Just don’t get any of your cum in me,” agreed Judy.

Mike continued rubbing her back, while he started sliding his big cock down between the girl’s legs. Mike kept on sliding his cock past the clenched lips of Judy’s vagina. Each time the tip of Mike’s cock slipped by the entrance to Judy’s vagina, he would push the head in a little, and let a bubble of slippery liquid lubricate the girl’s little hole.

Judy felt her brother pressing the head of his prick into her now slippery hole.

“Stop it!” she said.

“You almost went inside me that time.”

Mike resumed sliding his cock past the lips of his big sister’s vagina.

“Don’t you like it?” he inquired.

“Yes, but we shouldn’t,” she replied.

Still, Judy began working her hips in time with the sliding of her little brother’s cock. She enjoyed the slip-sliding feel of her brother’s penis rubbing against her pussy-lips.

After waiting a bit, Mike once again pushed the head of his cock against the opening to his big sister’s vagina.

This time, Judy didn’t stop him, as Mike let several big spurts of pre-cum lubricate his big sister’s hole.

“You aren’t cumming inside me, are you?” inquired Judy, worriedly.

“Just making it easier for my cock to slide, while I rub your back,” reassured Mike.

The next time that Mike felt the tip of his cock reach his sister’s hole, he pushed in a little harder. There was a popping sensation, and the little boy felt a ring of muscles slip over the head of his prick.

“You Little Bastard. You slipped your cock inside me, didn’t you.”

There was no heat in Judy’s accusation, and she didn’t pull away.

“I’ve just got the tip in,” lied Mike.

“It feels like more than just the tip,” grumbled Judy, but said no more, as she relaxed into her brother’s continuing backrub.

Mike continued to rub his sister’s back. Only now, he was sliding the tip of his cock in and out of the lips of his big sister’s hole, enjoying the sensations, each time the muscles of the girl’s vagina snapped around the head of his prick.

Judy knew what her brother was doing, but was enjoying herself too much to object. After a short while, Judy started to push back at her little brother. More and more of the little boy’s cock slid into his big sister’s belly, until the head of the boy’s prick rested against his big sister’s unbroken hymen.

“You’d better not knock me up, you Little Bastard,” said Judy, pushing back at her little brother.

Mike pushed his cock in and out of his big sister, until he knew he was close to cumming.

“Stop Judy!” he said.

“I’m almost ready to cum.”

“Don’t cum in me!” the girl cried.

“I don’t want to get pregnant!”

“Just wait,” he continued.

“No don’t pull off. Just hold on. If you pull off, I might cum inside you before you get all the way off. Just hold still. Don’t move!”

Mike grit his teeth, and fought down the sensations that almost had him squirting his seed all over the inside of his own sister’s tight little vagina.

Shortly, the boy felt a slight releasing sensation in his cock. He didn’t know if what he released inside his sister was cum, or just more lubricating fluid, but his prick was still hard, and the boy no longer felt like he was gonna ejaculate sticky white baby-juice all over the inside of his big sister’s tight little belly.

“Ooooh. OK,” he said.

“We can continue now.”

With this, Mike started fucking his sister, sliding his cock all the way up to her unbroken cherry, and all the way back out. Back and forth. Back and forth. Mike was really fucking his sister now.

After a while, it got to be too much for Judy.

“Stop,” she said.

“Huh?” Mike asked.

“I want to turn over, so that we can do it right,” she explained.

“Are you sure?” Mike wanted to know.

“Uhuh. If we are going to fuck, let’s do it right.”

With this, the girl turned over, and placed her brother’s big cock against the opening to her vagina.

“Now push,” she commanded.

Mike pushed, and his cock slid all the way up inside his sister’s belly with a rush. There was a snapping sensation, and Judy felt her hymen break. Then the girl started to climax, knowing that she had her own handsome little brother’s big baby-making cock stuck all the way up inside her tight little belly, where it belonged.

“Horny little bastard brother. You wanted to fuck me. Well fuck me!” she cried.

“You’d better not cum inside me though. I don’t want to get pregnant.”

Mike felt like he was in heaven. He slipped his cock in and out of his sister’s belly, enjoying the feeling of his sister’s vagina squeezing on his engorged penis.

Judy loved it. The girl hadn’t realized how good it would feel to be fucked. Soon, Judy found herself in the throes of a another even mightier climax.

“Cum. Cum. Cum. I’m going to cum!” she panted.

“Judy don’t,” warned Mike.

“You’re going to make me cum inside you.”

Judy was too far gone to stop. The climaxing young girl wrapped her arms and legs around her brother in a death-grip, and worked even harder.

“Unh. Unh. Do it,” she encouraged, not letting him go. “Squirt your cum in me. Knock me up.” couldn’t believe the words she heard coming out of her own mouth.

Mike couldn’t help himself. The boy began ejaculating big greasy ropes of thick white baby-making sperm right up inside his own sister’s tightly squeezing little belly. Rope after thick sticky rope of incestuous sperm squirted into the spasming belly of his sister, until both siblings were panting with exhaustion, and Mike had emptied his balls into his sexy big sister’s receptive young womb.

“Sorry Sis,” he apologized, “I couldn’t help it. Why didn’t you let me go?”

“I couldn’t” replied Judy, still panting.

“It felt so good, feeling you squirt that white stuff that make babies up inside my belly, trying to knock me up.”

Mike had to agree. It had felt soo good.

“Are you mad at me?” he asked.

“No, mainly, I’m mad at myself,” replied Judy.

“Why? I thought you said you liked it.” Mike was confused.

“I did. That’s why I’m mad at myself. When I think of all the wasted time, when we could have been doing this, I get mad.”

“You mean you’ll want to do it again?”

Mike couldn’t believe his luck.

“I thought you were scared of getting pregnant.”

“I am, a little. Still, even the thought, that I might be carrying your baby inside my womb, is kind of sexy. Don’t you think?”

Mike had to agree. The wondered of his baby, growing inside his big sister’s cute little belly, making it bulge, already had the boy’s penis swelling, and wanting more.

After a bit, the relaxation of after-sex letdown lulled Judy into falling asleep right where she was. Shortly, Mike was napping alongside his big sister also.

It was in this position, the two siblings sleeping, Judy with her brother’s sticky white sperm slowly welling out of her newly stretched little hole, and dribbling down her thigh, while a matching glob of white seeped from the end of the little boy’s prick, that their parents found them, about a half-hour later.