Ty suddenly had an idea. He'd read in books that girls' parts are way more sensitive to pleasure than guys' ones, and decided he wanted to experience it.
Looking a little forlornly at his member, he blushed, took a deep breath and said, "I wish my privates would transform into those of a girl."
Instantly, he felt a warm tingling between his legs. His penis shivered with stimulation and suddenly began to worm its way back into him, giving Ty intense pleasure as it got smaller and smaller. After it disappeared into his skin, his balls pinched up, causing him to start breathing heavily. His pants became higher and higher pitched as they too pulled up inside him, and he noticed how feminine his voice had become.
Then from around the skin between his legs, a little mound protruded out, a tiny fleshy blob. Then she felt a pleasurable pressure from it as it began to sink in at the middle and finally crack into a set of nether lips, causing her to make a feminine moan.
Something began to build inside her- a feeling of excitement making her feel girly and feminine all over. She grunted as a tiny nubbin and a peehole were forged above and inside her new parts, then gasped in surprise as she looked at her new body part... surprise and arousal.