Let's stay with Chris for a bit.

Chris could barely process what was happening to his body. The pecs he had worked so hard for were slowly disappearing underneath a layer of thick, soft and most importantly sensitive flesh. And yet he didn't find it in him to care, both hands firmly on the swelling mounds, kneading, pulling, rubbing until Chris felt dizzy with arousal. His neglected cock strained against the fabric of his swimming trunks, pre already starting to drool from the tip. The surfer couldn't remember ever having been this horny, not even when he had been in puberty. But such considerations where only in a small part of his mind; all that mattered was his chest. Pure pleasure radiated out from his nipples, making his jaw hang slack as moans rose unbidden from his throat.

"Ooohfffuuck, babe, this is awesome," Chris gasped, mashing his boobs together, grinning madly as he realized that they had gone beyond hand-filling. But his face fell when he felt them slow their growth. Luckily, even horny as he was, Chris quickly thought of a solution. "L-let me suck your cock again, I want them even bigger!"

No answer. Raising his head, Chris saw that he was all alone in the cubicle. Where had the cute redhead gone? They'd been having so much fun, hadn't they? **** on her cock had been the most incredible, arousing thing he'd ever done, the memory alone enough to make his breasts tingle and his cock twitch. Chris quickly lost himself in a fantasy of blowing her again, unconsciously slurping and sucking on nothing. The surfer could have sworn he could feel the thick organ slide into his throat again, making his neck bulge around its incredible girth, delicious pre pouring into him... Even the lingering taste was exquisite, but of course it paled compared with the musk of the real thing.

Luckily, it didn't matter. Chris new tits were unbearably sensitive, his fantasy too powerful, and soon, he was bucking his hips involuntarily, filling the cubicle with a variety of wet sounds as pre began dripping through his already cum-stained swimming trunks, spattering onto the sandy floorboards. His newly grown nipples could have cut glass, digging into his palms as he pawed and groped at his tits. Electric shocks were running up and down his spine, the surfer's fantasy growing more intense; the imaginary big-dicked girl grabbed his head to once again dominate him utterly, use his mouth as a fucktoy. So far, he'd always been the one to take the lead during sex, but he'd been missing out - nothing could compare to the incredible feeling of submission, of being at the mercy of another person. Already Chris could feel a tingling sensation build in his cum-filled belly, balls churning as they readied the next batch of cum. He was so close, the redhead in his fantasy moaning loudly as she announced her own impending climax, and--

"Yes, Mister Lifeguart, this vas vhere I saw them, and-- OH MEIN GOTT!"

Just when Chris came with enough **** to shoot his jizz through the fabric of his swimming trunks and send it flying to splatter on the bench, someone pushed open the door to the cubicle, only to recoil as he saw what was going on. Still in a post-orgasmic haze, tongue sticking out of his mouth, Chris turned his head to see a slightly sun-burnt, portly man in a shirt and bermuda shorts with a horrified expression stare at him. Behind him stood a musclebound man in the uniform of the beach's official lifeguards, his own expression quickly turning from bewildered to furious.