Mark continued trembling as the 10-foot draconic hunk that was once his little sister May continued to laugh his/her deep, echoing laugh, even as it evolved into more of a playful chuckle. "Oh, calm down, little bro," he said, giggling as he slapped his "little" brother on the back, accidentally knocking him over with his brute strength. "Even if I'm the big brother now, we're still related! I'd never hurt you...though I definitely will take advantage of the shift in power, hehe. Same goes for Sonia-- right, girlfriend?" The other buff dragon man giggled and nodded, before bending over to help Mark up.
Mark's head was practically spinning, both from his fall and his maddening attempts at reconciling the insane changes in size, age, sex, and even species of his former little sister and her schoolmate. Meanwhile, the newly grown dragons were busy flexing their massive, scaly biceps, bouncing their pecs, rubbing each other's abs, and basically just basking in their newfound enormity-- the fact that both girls had become adult males in the process of growing barely fazed them. Indeed, they both very much seemed to retain the mentality of a couple of bubbly, giggly little girls, even if the "giggling" part now sounded quite odd with their new booming voices.
"So, little bro," May began, making sure to emphasise those two particular words as she addressed he addressed his tiny sibling, "Don't ya wish you had guns like THESE~?" He grunted loudly as he performed a crab flex right by Mark's face, his thick, veiny muscles bulging enormously. Seemingly unnoticed by both "girls" were the towering erections they both now sported, no doubt still too young and unaccustomed to being male for them to realise what they meant. He and Sonia then launched into another of their bizarrely deep giggling fits, while Mark stared blankly at their muscular forms.