Sisters Instagram gets me going...

I don't know when it happened, but one day I noticed my sister was incredibly attractive! Her breasts had grown a lot in the years, and her beautiful plump ass tempted me more and more! Eventually I realized there was a gold mine of wank material when I found her Instagram. Seeing her at the beach with her friends wearing very little was hard to ignore... I dunno... I just started jerking it. Really hard. I managed to cum to a selfie of her sitting on the living room couch, fully clothed. I came a whole lot faster than I anticipated too. After feeling grossed out by myself, I cleaned up and went back into my room to continue my business. After maybe 2 hours of messing around, I started to feel horny again. Then I started thinking about my sisters perfect ass... And her perfect face... and her perfect... everything. I lied back down on my bed and opened her Instagram again. Within moments I was hard again, working my cock. Stroking hard and fast. I felt myself getting close to orgasm after only looking at 3 pics, none of which were all that sexy. Just her going about her day. It felt amazing to spill my seed thinking about her. In total I came 4 times to her throughout the day, all of which with her in my mind.

2 weeks later

I was in the bathroom with my phone sat on the counter next to me. I was masturbating to my sisters pictures again. I had filled my phone with pictures of her doing any number of things. Sipping boba, working out at the Gym, hanging with her friends, anything. One time she posted herself grabbing her breast with her tongue out. It was my favorite. After a little while, I heard the door open. My sister had walked in! I forgot to lock the door!

"Oh!-"

She exclaimed, seeing me rubbing myself furiously. Oh shit! She saw me jacking it... She saw me jacking it! I immediately started blowing my load. Squirt after squirt flew out of my dick as I had one of the best orgasms I've ever had! My sister watched me cum right in front of her! After about 10 seconds, I slowed down to a stop. I looked over and saw she had watched the whole time. She looked pleased? After a moment she feigned disgust.

"EW! You're jerking off to my Instagram pics!? What the fuck?! I should tell mom!"

"Please no!" I shout, covering my dick.

"I'll consider it if you answer my questions honestly."

"Ok!" I say, eager for her forgiveness.

"Is this the first time you've done this?"

"Umm.... no. I started a while ago."

"Really?" She asked, having difficulty hiding her excitement.

"Yeah. Maybe a week or two.

"Hmmm. How many times a week do you jerk off?"

"Uhh, I dunno. 3 to 5 times a day at least."

"3 to 5? That sounds like a lot! Do you always jerk to me?"

"...Yes" I answered ashamed.

She thought for a moment. "I'll have to punish you for this. It's our little secret, got it!"

"Yeah..."

"Good. Meet me tonight after bed. We'll talk about it then. In the mean time take the password off your phone and give it to me."

"Shit." I thought to myself. Busted.

Later that night, after jerking off once or twice more just imagining her watching me, I sneaked into my sisters room. The only lights on were some Christmas lights she had hung around the ceiling. She was dressed in a tank top with high cut jean shorts.

"Hey bro."

"Hey" I said awkwardly. She wanted something and it had to be bad.

"Look at what I did to your phone." She said as she handed it to me. The lock screen was an image of her sitting on her bed, pushing her chest forward towards the camera! That's so hot!

"Oh..." I said confused.

"How about this?" She swiped the screen, unlocking it. The home screen quickly appeared and it was another pic from the same angle, with her tank top removed! She still had her bra on, but I could see most of her tits!

"Wha? Why?"

"Take out your dick." She said in a command tone.

"What? You sure?"

"Do it."

I "reluctantly" agreed and removed them in excitement. My dick sprang out of my pants as I pulled them down. My sister grabbed a ruler from behind her pillow and kneeled down in front of me. Like she was ready to give me a blowjob. She pressed the ruler against the base of my shaft and looked closely.

"Hmm. 6 inches almost exactly. Not bad. A little bigger than my first boyfriend." She teased as my cock was twitching wildly. Her hands were so close! I'm gonna cum!

I groaned a little as I started cumming on my sisters tits! I instinctively grabbed myself and started rubbing hard! Oh my god! She's gonna kill me when I'm done blowing the biggest load of my life all over her face! What felt like years of orgasm passed and I looked down at the mess I had made. She was smiling and looked shockingly pleased with the situation. In fact, she started eating my cum!

"You are gonna send me a picture of every orgasm you have from now on." She said as she stood, wiping off my cum and putting it in her mouth.

"Seriously?"

"Yep! And I want every single one to be to ME! Nothing else!"

"Ok!" I said, incredibly excited by the idea

"From now on, I want you to cum 8 times a day at least!"

"8? I can't handle 8!"

"You can and you will! If you miss even a single day, I WILL tell mom and show her everything that's on your phone!"

"I guess I'll try."

"Good. Starting tomorrow, show me every orgasm."

The next day it was hard to believe what had even happened. My sister WANTED me to cum to her face! Many times a day even! And I was so excited to get started! My sister wore only a bra and panties to breakfast. Our parents were out for the weekend so she didn't have to worry. She pulled a chair from the opposite side of the table and placed it very close to mine, and took a seat.

"Hey big bro." She whispered in my ear.

"You have a lot of cumming to do." She said as she reached for my hardening cock. She began rubbing it through my sweatpants as she pressed her boobs on my arm.

"So you better get started soon. Send me the evidence when you're done." She said before letting go of me to get started preparing her breakfast.

I was so incredibly aroused I could hardly stand it. I sat up and pulled my dick out. I couldn't stop rubbing as hard as I could. God she was so hot! I looked at my sister as she noticed what I was doing.

"God damn you are such a horny boy! Cum for me!" That was all I needed. I came all over myself after maybe 25 seconds of rubbing as hard as I could.

"I guess you don't need to take a picture of this first one! Teehee!" She giggled as she continued making her breakfast.

The next day she say next to me on the couch and kissed me on the cheek. I came with her sitting next to me, telling me she wanted to see me cum.

After the weekend we had to get back to our usual schedule of work. It was really tough to jerk off 5 times during my shift. I was worried people were gonna notice. I hope they didn't. After the whole work week, our parents were home and we didn't want to risk anything. But I kept sending her my loads, and she kept telling me how much she loved it. 2 months had passed and we had hardly been able to see each other the entire time. But one weekend our parents took another trip without us.

"Bye!" My sister said as she shut the door behind them, locking it.

"Man that was WAY too long! Come here!"

She said as she approached me sitting on the couch. She sat on my lap and wrapped her arms around my head, kissing my cheek.

"I wanna see something." She said as she grabbed the ruler from between the couch cushions.

"You've been jerking quite a lot. I've heard excessive masturbation shrinks the penis. I wanna see if that's true." She said casually as she worked on my pants, exposing my erect cock.

"What? I've never heard that." I said, in disbelief at the idea.

She pressed the ruler at the base of my dick and looked again.

"Ah. See! 4.9 inches! Wow that's a good bit lost!"

"What?" I say, attempting to sit up with he still on top of me.

"Yeah! Look! I'm even pressing the ruler all the way down." She says as she stands up next to me. I take the ruler and push my dick outwards and give it another look. Oh man really? Over an inch? It's gotta be a weird measurement or something, I rationalized with myself.

"But you better keep it up! I swear I'll tell everyone if you ever stop cumming to me! In fact, I think I'll up the steaks. 10 orgasms a day!"

"Ten!? I can barely keep up with 8!"

"Well that's too bad! If it's not really shrinking, you've got nothing to worry about! If it IS shrinking, you've got quite the trouble on your hands." She said as she walked away.

Oh man, How was I gonna deal with this? She's so hot... I don't want to stop cumming to her. But I'm not sure if I really am getting smaller...

Bzzt

She had sent me an image. It was her lying naked on her bed, touching herself.

"Here's some encouragement." The text read.

During the next month I began obsessively measuring myself. She kept sending me nudes and it was so hard to resist. I think she was right. It was definitely smaller than before, and it was ever so slowly dwindling away. But I couldn't stop cumming for my sister even for a day.

After another month we got another day alone. I was so embarrassed to see her bring the ruler in my bedroom shortly after I woke up. She whipped the covers off to find my little boner bulging in my underwear. She crawled onto my bed and quickly tugged my super hard penis out of my underpants. She swiftly pressed the ruler down and gasped.

"Oh my god! Wow! You've destroyed yourself for me! Your sister! Hahahahaha!" She laughed the hardest I had ever seen.

"It's 2.4 inches! That's medically a Micro-Penis!" She cackled to herself, proud of herself for ruining me so thoroughly.

"I'm gonna cum-" I manage to get out before I start blowing my load all over myself. She grabbed my nub and started rubbing quickly. It was so hot to me. I wanted to go further.

"Can we keep going?" I ask her, coming down from orgasm.

"Haha! Sure! I wanna see how small you can get! My brother has a baby dick and he wants it to be smaller!" I felt so aroused, but tired.

From then on she'd give me handjobs, titjobs, and even blowjobs as often as she could. Sometimes multiple times a day. We started getting closer and making out and touching each other every moment we could get away with it. She was determined to keep me cumming. After another month came another measurement. I couldn't believe it.

"Oh my GOD! Wow! Just 2 inches! It's barely even a nub! More like an oversized clit!" She said with glee, jerking me off.

"I'm so proud of your progress!" She kissed me before leaning down and kissing the tip. Shortly after she started swirling her tongue, I blew a small load in her mouth. She swallows.

"You're never gonna have a decent cock again. It's amazing how dedicated you are to me."