Rio de Janerio

The stuffy, crowded bus ride back to our hotel in Paraty after a wild day at the Mardi Gras in Rio was long and uncomfortable. My head was still spinning from the cocktails and the sensory overload of the carnival - the pulsing music, the colorful costumes, the energy of the crowd. But most of all, my body was still humming with lust from the flirting and groping I'd received throughout the day.

I glanced over at my older sister Emily sprawled out next to me on the narrow bus bench, snoring softly with her head on my shoulder. She was still gorgeous, even with makeup smeared and hair a mess. Her shirt was unbuttoned, revealing a tantalizing peek of cleavage. Just like me, she was still wearing her skimpy party clothes - a barely-there crop top and miniskirt that left little to the imagination.

As the bus crawled along the winding roads, the air grew thicker and hotter. Sweat trickled down my neck and back. I shifted uncomfortably, my skinny jeans feeling too tight. The heat only made my body more sensitive, every brush of fabric against my skin electrifying.

I gazed out the grimy window at the passing palm trees and lush vegetation of the Brazilian landscape, a far cry from our typical suburban life back home. Coming to Paraty for Carnival with Emily had been my mom's idea as a way for her to get over her breakup with her douchebag boyfriend Harry. She'd insisted I tag along as a chaperone, which I thought was dumb, but now I was kind of glad to have this exotic adventure with my cool big sis.

The bus hit a pothole, jostling us both. Emily mumbled in her sleep and shifted, now draped across my lap. I breathed in her sweet scent, a mix of coconut sunscreen and something uniquely her. Even sweaty and drunk, she was irresistible. My eyes drifted down to the hem of her skirt riding up, revealing tantalizing glimpses of smooth thighs.

I knew I shouldn't, but I couldn't help myself. Slipping a hand under her skirt, I slowly trailed my fingers up her inner thigh. She felt so soft, like warm velvet. As I inched higher, I was shocked to discover she wasn't wearing panties. My fingers brushed against her bare pussy and I felt how wet she already was.

Emboldened, I slid one finger inside her. She moaned softly and shifted her hips against my hand. I couldn't believe what was happening, fondling my hot sister on a crowded bus. But no one seemed to notice or care in the dim light. Everyone was either asleep or looking out the windows.

I pushed up her top, freeing her breasts from her bra. They were even more perfect than I'd imagined - full and round with dusky nipples. I palmed one, feeling the weight of it in my hand. She let out a breathy sigh that sent a shiver down my spine straight to my cock.

My other hand crept under her skirt to play with her now dripping pussy. She was so hot and slick, her wetness coating my fingers as I thrust them in and out. She started squirming and panting louder, not caring who might see or hear.

Panic mixed with lust as I looked around the bus. In the seat across from us, an old man was watching me with interest. Our eyes met and he smiled knowingly, then looked pointedly at my sister's bare tits before winking at me. I felt a thrill seeing him enjoy the show.

"Hey, let's give this old guy our seats," Emily suddenly said, sitting up and pushing me out of the way. I felt a pang of disappointment as she abandoned me.

But then she plopped back down on my lap facing me and hiked up her skirt completely, exposing her bare pussy to anyone who glanced over. Before I could react, she straddled my hips and rubbed herself against the bulge in my jeans.

"Emily, what are you doing?" I hissed in shock. "Someone will see!"

"I know," she breathed. "Isn't that what makes it so hot?"

She unzipped my fly and pulled out my throbbing erection. Without warning, she sank down on my cock in one smooth motion. We both gasped at the sensation of finally joining. She was so tight and wet, gripping me like a vice as she started to bounce.

I grabbed her ass to steady her as she rode me hard and fast. Her breasts jiggled hypnotically inches from my face. I latched onto one nipple, sucking and biting as she ground against me.

"Fuck Sam, your cock feels so good," she panted. "I'm gonna come."

The old man stood up and came over, watching us with blatant desire. Without asking, he reached out and squeezed Emily's tits, rolling her nipples between his fingers. She just moaned louder and kept going.

I was overwhelmed by sensations - the feel of her hot pussy clenching around me, the sight of this stranger playing with her tits, the risk of being caught fucking my sister on a bus full of people. It was all too much.

With a grunt, I exploded inside her, filling her with my seed as I pulled her down hard onto my cock. She screamed as her own intense orgasm ripped through her, spasming around me as I pumped load after load deep inside her unprotected womb.

We collapsed against each other, gasping and shuddering in the aftermath. The old man zipped up and returned to his seat with a satisfied smirk.

No one else on the bus said a word or even looked our way. I guess they were used to this sort of thing at Brazilian Carnival. But for Emily and me, it was a mind-blowing, taboo experience we'd never forget.

Back at our hotel room, we pushed the twin beds together like they were always meant to be one. Exhausted, we passed out in each other's arms, my softening cock still nestled inside her. In the morning, we made love again - slowly this time - basking in the forbidden glow of our secret tryst.

For the rest of our trip, we played it cool in public but couldn't keep our hands off each other behind closed doors. By the time we flew home, I knew things between us had permanently shifted.

Back in reality, Emily acted like nothing had changed and Harry was history. But I knew better. I knew the real reason for that secret smile on her face and the extra sway in her hips. And I knew there was no going back from here.