A thought popped into Rebecca's head, one she felt a bit ashamed for thinking. "I thought of something, but, uhh... it's a bit weird," she admitted.
"Go for it," Ty grinned.
Blushing, Rebecca replied, "I... um... give me a cock," she mumbled.
"Sure," Ty grinned. He wished for it, and Rebecca pulled off her skirt and panties, her heart racing as a weird feeling filled her crotch. Ty watched in amazement as her pussy sealed up, two lumps dropping into it while her clit swelled rapidly. The tiny nub expanded as both of them watched until it poked out about 6 and a half inches from her crotch.
As the changes finished, Rebecca smiled and stood up from her desk chair, her new shaft in line with Ty's mouth. To his surprise, the sight and scent of the cock turned him on, and he quickly found himself sucking it. Rebecca moaned approvingly, "Fuck yeah, you give good head," as she humped against his mouth. It was strange to be pitching, she thought to herself- the motions and the kind of pleasure were so different.
But before she came, Ty pulled away, to a mix of frustration and concern that he hadn't enjoyed it. But to her relief, he cast off his jeans and boxers, and spread his legs as he said teasingly, "Lemme give you somewhere to put that." Instinctively, she grabbed her shaft and started fapping as Ty's manhood receded. His balls slid up inside him, and his crotch tucked inwards where a few minutes ago hers had stretched outwards. His cock shortened inside him rapidly, feeling more and more sensitive as it shrank, and a slit opened down the centre of where his scrotum had been, creating a pussy hole that almost instantly started to moisten.
The moment she saw that, Rebecca couldn't hold back any longer. The tip of her cock kissed his, and a split second later his cock had finished becoming a clit. She moved downwards until her penis entered his vagina, and both of them gasped and moaned as their changed anatomy gave them unfamiliar feelings of lust and pleasure. Ty reached up and softly cupped Rebecca's boobs, and the girl gasped as she came, the first of her semen flowing rapidly; in response to the feeling of being cum inside, Ty couldn't hold back and came around her with his new pussy walls clenching her shaft. Neither of them could make any conscious moves by now- their minds were blank and their newformed parts were doing everything.
They panted and came down from the high a minute or so later, kissing messily. Neither could say a word, but both knew this power was fucking awesome.