Ten minutes of filthy roadside sex later

Ben squealed loudly as Adrian's cock shuffled his internal organs with every thrust. Ben's clit-dick was drizzling thick milky pink fluid in a pond beneath him. Pooling around his knees, there was at least a pint of Ben's pre-cum. It tasted like strawberry ice cream and was more useful as a lubricant than semen.

Not that it mattered. Ben's testicles had disappeared, leaving only his thumb-sized dick above his taint to drizzle helplessly. His prostrate, while hard to see, bulged against his belly when a Cock **** its way past it. It was probably about the size of a grapefruit and also lubricated his colon. Milky pink froth gathered around Adrian's cock.

Ben's butt plug laid on the car's back seat in front of him. Every other moment, Ben glanced down at it. It grew larger and larger the more pleasure he felt. One inch, two inches, three inches. And every time, Adrian's cock grew bigger and penetrated deeper. six inches, nine inches, fifteen inches long. Every time he pulled out for a moment and let his cock rest under Ben's drizzling clit, Ben could see it was changing.

The head of the cock was flaring and becoming flat, the skin color changed from normal human into a pitch black spattered with pink spots. A Pretulial ring manifested on the middle of Adrian's cock and began slipping inside of Ben's asshole. Ben moaned higher and thrust back against his beastly master.

Adrian hadn't noticed anything had changed. A horse tail, a hundred pounds of extra muscle, an extra foot of height, hooved feet. His face elongated slightly, he started snorting air out of his larger nostrils, and his teeth seemed to grow bigger as his ears travelled to the top of his head and morphed into horse ears. Four stubby fingers on his massive hands. Darker skin, black eyes, natural make-up.

Everything Ben could wish for in a primitive roadside lover. As Adrian seemed to climax, he suddenly tripled his pace, causing Ben to squeal wildly with painful pleasure as his body climaxed together with him. Ben felt Adrian's large testicles twitch against his thighs as he felt his seed coat his insides. Adrian pressed himself as deep as he could inside of Ben while he emptied himself, gently biting Ben in his shoulder. "Just what I needed, Ben," Adrian said in a hushed tone a minute later as he slowly began pulling himself out. "Thanks for the rut."

"The same," Ben said as he picked up his butt plug and got ready to quickly put it back inside himself. As Adrian's flared cock got pulled out with a deep plopping sound, Ben easily slipped the three inch wide plug into his gigantic and inhumanly flexible asshole. Ben smiled with pride at the sensation of the even bigger toy filling him up, as well as the sloshing sensation of Adrian's musky seed inside of him.

As Ben crawled out of the car and stood on his legs, he felt a bit off balance and his shoes made a weird clopping sound. He glanced down and gasped as he noticed he'd changed more than just on the inside. His feet had morphed into hooves, wearing horseshoes that resembled human sandals, but with hard rubber clamped to the hooves. Ben then noticed his hands had only four fingers, like Adrian's but much smaller and more delicate. He turned around and saw his face in the window of the car. He didn't have horse ears, but his teeth did look bigger.

"Looking for your skirt?" Adrian said in a baritone voice as he came over to Ben, a bit more apologetic than the horny brutish welcome he'd given him ten minutes earlier. He held Ben's denim skirt for him to pick up.

"Thanks... I could have sworn I had shorts," Ben said as he took the skirt. "And panties..." he said as he found his underwear, beating the roadside dust out of it before putting it on. As he did, he realized his hips had expanded to make room for his even larger donut-puckered asshole and massive prostrate. Memories of him stuffing his hands inside himself, caressing and stimulating his new organ, began to appear in his mind. Some part of him thought it was very weird, but most of him just thought of it as fond memories of being a horny teenager exploring his body.

"Guess I gave you cum brain," Adrian said with a chuckle and patted Ben's head. Ben pouted but rolled his eyes and playfully punched Adrian in the shoulder. Then he got a worried look on his face. "Where's Matt and Noah?" he asked, glancing around Adrian's vision-obscuring frame. "Matt?" Ben called out?

"Just a minute," a feminine voice said from behind Matt's car. A moment later a feminine Matt came into view, walking awkwardly while pulling up a pair of denim shorts.

"Sorry, we didn't want to disturb you two," She said with a sheepish smile.

"Matt, you've changed," Ben said in a high tone, clopping over on his hooves and grabbing her by the shoulders. "you put the bracelet on?"

"You're one to talk," Matt said as she saw Ben's humanoid hooves, wide hips and four-fingered hands on her shoulders. "Filly-Ben," she said as she put a hand on Ben's head and ruffled her hair. Matt was still tall and muscular compared to Ben, who might have gained an inch or two in height with her new long dainty legs, but she was still pretty small and cute.

"I thought you guys came to pick us up in the same car," Adrian said as he lumbered over to Matt and Ben with the last of the luggage, cleaning sweat and bodily fluids off his arms with a massive wet napkin sheet. He was wearing chaps as trousers, his massive horse member out in the open. Forcing horse-men to wear constrictive human clothing had been banned since the civil rights movement.

Matt inhaled and went silent for a second as she took in Adrian's new form. "We keep our eyes on the road when we're driving," she said as she shook her head and blinked rapidly, shooing away indecent thoughts. "And I think we better get going, Jake and Amber are probably missing us."

"I'll vote for that," Noah said as he came around from behind the car as well, buckling his pants. "While we all have the clarity to keep our eyes on the road," he said as he wrapped a hand around Matt's shoulder.

Mat rolled her eyes but smiled and leaned into the slightly shorter man, giving him a look as if he's barely passed a test but it was a difficult test. "It's just a two hour drive or so. I think we should be able to get there without creaming our pants... or the floor," Matt said and gestured at Adrian's air-cooling deflating horse cock and Ben's derriere and wet inner thighs. Ben had found one of Adrian's massive napkin sheets and was using it to dab off the worst mess off her body.

"Ben?" Matt said, crossing her arms.

"Uh?"

"We need to talk, soon, but... Where's your top?"

Ben looked down at her topless chest before she glanced around. Not that he really needed anything to cover his bee-sting tits, but he looked better and more decent with it on.

"I knew there was something I'd forgotten..." he said as he galloped after a flimsy piece of white clothing that had begun fluttering in a small wind. The rest laughed and began packing the last bags into Matt's car.