The park was dark except for the weak glow from the streetlights along the path. Mark had come out here after midnight because he couldn't sleep and his girlfriend was out of town. He told himself he just needed air, but his dick was already half hard from the porn he'd been watching on his phone. Straight porn, the usual stuff with big tits and loud moans. He sat on a bench near the trees, rubbing himself through his jeans, when footsteps crunched on the gravel.
A guy about his age, maybe thirty, walked up. Tall, built, wearing a tight black t-shirt and shorts that showed off thick legs. He stopped a few feet away and looked straight at Mark's hand on his crotch.
"You need some help with that?" the guy asked, voice low and rough.
Mark froze. He was straight, married to a woman, never even thought about guys before. But his cock twitched hard at the words. "Fuck off," he muttered, but he didn't move his hand away.
The guy stepped closer. "Name's Derek. I saw you stroking. Bet that straight cock wants something different tonight." He reached down and grabbed Mark's wrist, pulling the hand away and replacing it with his own. Derek squeezed through the denim. "Yeah, you're fucking hard. Let's see it."
Mark should have shoved him off. Instead he sat there while Derek unzipped his jeans and hauled out his thick seven-inch cock. The night air hit it, then Derek's callused hand wrapped around the shaft and started stroking slow and tight.
"First time with a guy?" Derek asked.
Mark nodded, breathing hard. His mind screamed this was wrong, but his hips pushed up into the grip.
Derek dropped to his knees on the grass. "Then I'm gonna suck this straight dick until you beg me to fuck your ass." He leaned in and swallowed Mark down in one go, lips stretching around the head, tongue working the underside. It was hotter and wetter than any blowjob Mark had gotten from his girlfriend. Derek bobbed fast, gagging himself on the length, spit running down Mark's balls.
Mark groaned and grabbed Derek's hair. "Shit… that feels too good." His straight brain kept trying to shut it down, but his cock was leaking into Derek's throat. Derek pulled off, stood up, and shoved his own shorts down. His cock was longer, curved, already dripping. He grabbed Mark by the shoulders and turned him around on the bench.
"Hands on the backrest. Spread your legs." Derek spit on his fingers and shoved two straight into Mark's hole without warning. Mark yelped at the burn, but Derek worked them in and out, twisting, opening him up. "Tight virgin ass. Gonna feel so good wrapped around my cock."
Mark's face burned. He was straight, for fuck's sake, but his dick was throbbing and his hole was starting to push back on those fingers. Derek pulled them out, spit on his own cock, and pressed the head against Mark's entrance.
"Breathe out," Derek ordered, and pushed.
The stretch was brutal at first. Mark hissed and tried to pull away, but Derek held his hips and kept shoving. Inch after inch sank in until Derek's balls pressed against Mark's ass. "Fuck, you're taking it all. Straight guy getting his first dick in the park like a slut."
Derek started thrusting, hard and deep. Each stroke punched the air out of Mark's lungs. The pain faded into a raw, full feeling that made his own cock bounce and drip onto the bench. Derek reached around and jerked him in time with the fucking. "Tell me you want it."
"I want it," Mark gasped, voice cracking. "Fuck me harder."
Derek obliged, pounding faster, the bench creaking under them. Skin slapped loud in the quiet park. Mark's hole clenched around the invading cock, milking it without him meaning to. Derek's free hand smacked Mark's ass cheek. "Gonna breed this straight hole. Fill you up so you feel it tomorrow."
Mark came first, shooting thick ropes across the bench while Derek kept slamming into him.
The orgasm ripped through him like nothing he'd felt with a woman. Derek followed seconds later, burying deep and pumping hot cum into Mark's guts. He stayed inside, grinding, letting every drop drain out.
When he finally pulled free, cum leaked down Mark's thighs. Derek turned him around and pushed him to his knees. "Clean it." Mark opened his mouth without thinking and sucked the softening cock clean, tasting his own ass and Derek's load. Derek patted his head. "Good first time. Come back tomorrow night if you want round two."
Mark stayed on his knees after Derek walked away, breathing hard, hole sore and leaking, cock already twitching again at the thought. He wasn't straight anymore, not after that.
