Eric recited his spell as best as he could recall it and nothing at first happened. Eric shrugged and was about to turn when his eyes grew wide as he began to notice the changes in his sister. She moaned a bit in pleasure as she herself began to feel the changes take place. Slowly she grew more than a head taller than Eric, with almost all of her beefing up in some way while tearing apart her clothes.
As the changes slowed, Penny started to take account of the situation: "What the hell, Eric? It didn't work! My breasts are bigger than before your spell!" She squeezed her breasts and gave a little lady moan at how sensitive they were.
Eric would have been transfixed by the tall, Amazonian beauty of his sister if it hadn't been his eyes had spotted the "surprise" early in the transformation, "Uh, Penelope?"
Penny let go of her breasts and glowered at Eric, "What?"
Eric shivered a little bit, "Well the spell did make you a man in the one place that it really counts." Penny finally noticed where her brother was looking and began to slowly bend down to see past her large breasts. There upon her crotch was a huge penis, rather erect from the play upon her sensitive nipples. She reached down to touch it gingerly, as if she was afraid it might bite and then she gave a very girly giggle and excitedly exclaimed, "Oh thank you, Eric! Maybe I can get into the school with this!" She proceeded to tightly hug her brother, who was somewhat weirded out by the combination her breasts nearly crushing into his face and her cock sandwiched between them in the hug.