I made a truly fucked up deal with my sister

All characters are at least 18 years old.

Franny, my sister, had been eyeing me all evening, a mischievous smirk playing on her lips. The fact that she wore nothing but a thong and a bra also raised my suspicions, along with something else.

"Hey bro," she said, sauntering over to me on the couch. She held a plate of warm cookies below her big perfect tits. "Want to make a deal?"

I raised an eyebrow, wary of her intentions. "What kind of deal?"

Franny's smirk grew wider. "Every time you let me to squeeze your balls," she began, her eyes gleaming, "I give you a lap dance that makes you cum."

I was surprised she asked for this, but not shocked. I knew she had a thing for ballbusting with how many times she had slapped my balls for annoying her, and kicked many guys' balls at school. Plus, we'd made deals where if she promised not to tell our mom whatever stupid thing I'd done, then I had to kiss her butt and pussy while she wore panties.

Even though I've desperately wanted my sister sexually, I had to at least first pretend like I didn't.

"What? That's gross!" I exclaimed, feigning disgust and trying to keep my growing erection hidden from her. "Why would I agree to something like that?"

Franny plopped down next to me, her luscious thigh pressing against my muscular thigh. She leaned in close, her delicious lips against my ear. "Because," she whispered, "I know the power I have over guys. Plus, I'm your sister. I'm so forbidden, and I know that makes me even more tempting to you."

Her hand reached out, massaging my hardening cock. "Come on, I could feel that you want it. It'll just be a little nut squeeze."

I swallowed hard, my resistance crumbling like a cookie in her mouth. "Alright," I managed to croak out, "But it's not that I'm attracted to my own sister. I just feel like cumming."

Franny took off her bra, then wiggled her tits near my drooling, hypnotized face as she said, "Yeah, sure you're not attracted to me."

She slid her hand into my underwear, nudged away my pulsating cock, and then grabbed my balls. I flinched and gasped.

She squeezed my balls. Her fingers and palm pressed in all around them, sending a jolt of pain without end, only getting more intense. I groaned and grit my teeth. I kept telling myself it was a pain I could endure if it meant a heavenly lap dance from her, but she kept squeezing harder and harder. The agony was too brutal. I knew I would have to call off the deal at any second.

"Now, remember," she cooed, "Every time you let me do this like a good boy, you get your treat." The devilish spark in her eyes was unmistakable as she squeezed even harder and twisted my swelling balls. I wretched and my whole body shook.

She shouted, "Oh yes! I love dominating your balls!"

Franny kept switching from gently playing with them to viciously shaking them. I was completely helpless as she indulged. I was just about to call the deal off, but she finally let go.

"So, are you ready for your treat?"

My eyes watered from the pain, but I nodded. Franny strutted over to the sound system, her ass swaying like she was auditioning for a music video. She picked a slow, seductive song.

She began to dance, her hips rolling in time with the beat. She stepped closer, and my cock pulsated harder with each shake of her ass and tits.

Franny pulled my now bare cock through my fly. Just her touching it felt so good I thought I might cum. She sat on the underside of my erection, and began to grind her ass into it. The pleasure of her body and the pain in my balls created a mix of intense sensations.

Her hands reached back and grabbed my thighs for support as she moved in a sensual rhythm. Her bare cheeks slick with sweat. Those perfect mounds engulfed and rode my cock. My eyes were glued to the hypnotic bouncing of her tits. I grabbed them and played with them.

Franny took off her thong. She leaned forward and took me inside her pussy. Her walls clenched as she went wild with my cock, her shaking ass in full view. Each movement sent waves of pleasure. I could feel my balls tightening, and the pressure building up as she brought me closer and closer to the most epic orgasm.

Her moans grew louder as she picked up the pace. It was too much. I knew I was about to cum.

She said, "You've always wanted to fuck your sister, haven't you?"

I couldn't help but speak form the heart. "Always! You're the hottest girl in the fucken world!"

She looked over her shoulder at me with the most demonic grin. Just before all the pent up desire I've had for her was about to be released, she squeezed my balls harder than ever.

I tried to scream from the sudden agony, but all that came out was a squeak. My nut-nerves were on fire as her flesh sunk deep into my swollen manhood.

"Sorry bro, they're so big and juicy, I couldn't resist, just like you couldn't resist me."

Barely able to get the words out, I said, "Please let go. I need to cum. I need to cum. Please, please."

Franny shouted, "Oh god! That begging sounds so good!" She then twisted and tugged on my balls.

I shrieked with the last bit of air in my lungs as my body twitched.

The room was a cacophony, Franny's moans, my desperate whimpers, and the wet slap of her body on mine. She leaned back into me, her breasts moving up and down as she breathed hard and continued fucking. I glared down at her serene face looking back at me.

She kept riding my cock as she worked my balls, giving herself the most epic orgasm.

After catching her breath and cackling at my expense, Franny said, "That was two squeezes, so I guess I owe you two orgasms now." She giggled and said, "Maybe tomorrow."