Luc was so excited for the family road trip in his dad's new car. At 14, he had been looking forward to it for weeks. He had his backpack full of snacks and his favorite video games. But then his annoying older stepsister Stacy came bounding out, her large breasts bouncing.
"Can I come too, Daddy?" she asked in her whiny voice.
"No Stacy, there's no more room in the car," Luc's dad said.
"Please? I'll sit on Luc's lap," Stacy whined. Luc rolled his eyes but his dad just shrugged.
So Luc squeezed into the backseat and Stacy plopped down on his lap, her huge butt squishing against his crotch. Luc felt his penis stiffen at the contact. She was surprisingly heavy and soft. He tried pushing her off but she squirmed away.
"Oooh, someone's happy to see me!" Stacy teased, noticing Luc's boner poking her ass. She reached back and rubbed it through his shorts. Luc blushed red, mortified.
As the car pulled out of the driveway, Stacy let out a huge, loud fart. Ewww gross! Luc pinched his nose. Stacy giggled. She did it again a few minutes later, even louder and stinkier. The next time, Luc whapped her butt.
"Ow! Quit it, dweeb," Stacy snapped. Then she buried her face in Luc's neck and whispered, "Unless you wanna put that hard dick in my butt. That'll muffle the smell."
Luc's eyes went wide. He had never even kissed a girl before, let alone fucked one. But Stacy was already hiking up her skirt and pulling her panties to the side.
"Well c'mon, shrimp, stick it in before I fart again!" she growled, frustrated.
Luc's dick throbbed, aching to penetrate. He pulled it out and tentatively rubbed the tip against Stacy's puckered hole. She reached back and pushed his cockhead in. Luc gasped at the vice grip.
"Ohhhh fuck, you're hung!" Stacy moaned, wrapping her thick thighs around Luc's waist. Luc slowly pumped in and out of her tight ass. Stacy squealed with delight and slammed back against him, devouring his cock.
Whenever she felt a fart brewing, Stacy would bury her face in Luc's neck and he'd stick it back in her butt, muffling the noise. Luc fucked her quietly as his dad drove, Stacy's boobs jiggling each time she bounced on his dick. He'd never done anything so naughty. Stacy made him feel like a man.
After a while, Luc felt that familiar pressure building in his balls. "I'm gonna cum!" he warned Stacy.
"Then pull out and shoot it on my face," she said breathlessly. "I wanna see it squirt."
Luc yanked his cock free and stroked like mad. Stacy turned and opened her mouth. Thick ropes of jizz painted her face and tits. Stacy scooped the cum onto her fingers and sucked them clean.
"Keep this a secret and we'll do anal again sometime," Stacy said with a wink. "I knew you had a big dick, little bro. Let's trade videos too. I wanna see what that cock can do."
Luc nodded eagerly, already hooked on fucking his rude stepsister's ass. What a road trip it turned out to be! He couldn't wait to do her again when they got to the hotel.