"Ok," Crystal's voice is little more than a whisper. "Ok as long as you're the one doing me that's fine."
"You sure?" Cassie leaned a bit closer to her friend.
In answer Crystal quickly grabbed Cassie and kissed her. Kyle could tell that there was more than just lust behind the kiss and he had the odd sensation of intruding on an intimate moment. He almost considered leaving when he saw Cassie start wriggling out of her jeans and exposing her rear to Kyle. Using both her hands she stripped off her panties and then wagged her hips back and forth for a bit. She stopped kissing Crystal just long enough to say: "Don't keep me waiting," before going back to kissing her friend.
Kyle took her advice and jumped up behind her on the couch. He didn't need much to get erect it seemed and started pressing his rod against Cassie from behind. Cassie cooed and reached back to take hold of his member with one hand before sliding it into herself. She let out a little gasp as their hips met and she looked over her shoulder at Kyle. "Don't start pumping until I get her pants off."
Kyle nodded and, to his embarrassment, gave a little ribbit. Cassie giggled and crouched down to start stripping off Crystal's pants. With Crystals enthusiastic help she was soon naked from the waist down. As soon as Cassie bent down to start pleasuring Crystal, Kyle took a good grip on her shoulders (easier than he'd thought it would be thanks to small sticky pads on his frog fingers) and started to work his cock in and out of her.
Slowly at first but gaining speed to the point where he was producing small smacking noises with each thrust, he felt his orgasm approaching. Eventually with one last noise that was between a grunt and a ribbit he thrust into Cassie and shot his frog load into her.
The way that Cassie trembled as he came suggested that she'd experienced a similar orgasm but she didn't waver in her attention to the now loudly moaning Crystal. Kyle sat back and watched, a bit worn out from the constant sex of the past few hours, to watch as Cassie's skin took on a green hue. She went through the same expected physical changes as the others as well. Her breasts were soon struggling against the confines of her shirt and her ass took on an intoxicating shape and definition. Kyle couldn't see the changes in her hands but he could watch as her feet and legs became more and more froggy.
A sudden and intense squeal from Crystal told Kyle that Cassie's tongue had just grown and it was no surprise that Crystal was soon shaking with an orgasm. What was a surprise was when Crystal started to change as well. It had taken more than his tongue to change Samantha, but then it may work different for girls's tongues. "Well... shoot," Kyle said, knowing what Crystal's preference had been.
Crystal's skin started turning green as well, though to Kyle's surprise it didn't reach quite a dark a green as his and the girls's. He saw Crystal's breasts begin to put on some serious size and he could only guess her bottom would follow suit like the other girls's. However her hands, feet, and legs remained distinctly human and when Crystal's tongue lolled out of her mouth it was certainly longer than a human's but still only dangles past her chin rather than Kyle's tongue which he was fairly certain could lick his own feet if he chose.
As the last of the girls's orgasms faded both Cassie and Crystal took stock of their new bodies. Cassie was obviously pleased but it was a bit harder to tell what Crystal was feeling through her post-orgasmic haze.