The teacher stands up again to present something on the whiteboard at the front of the class, showing off her obscene bulge through her leggings in the process. However as she talks, you can occasionally hear cracking noises from her direction, and she occasionally grunts. You realise after a few minutes that her posture is slightly different, changed from a more feminine posture to a more masculine posture, with wider shoulders and thinner hips. Her voice becomes slightly deeper and louder as she speaks, and her shoulder-length hair pulls into her scalp and lightens in colour, leaving her with a short, stylish, light brown haircut. You suddenly realise that by giving her a penis, you altered reality to change her into a man! You try to reverse the change, but decide to just let it happen and enjoy the show. Her breasts flatten out a bit, but still stay fairly large as they become firm and solid pecs. Her round chin loses its fat to become a defined square chin, matching her nose which cracks into a straight shape. Her eyebrows become bushier, and her cheekbones become narrow, clearly forming her face into the face of a very attractive man. His biceps swell with muscle, stretching the light fabric of the loose t-shirt, and his abs tighten and become a chiselled six-pack underneath the shirt. As his thighs become thick and sturdy, his stretched clothes reshape themselves on his body. His shirt becomes a light Nike t-shirt, and the tattered cardigan becomes an Under Armour running jacket, tight enough that the teacher's large nipples are visible poking through the material. As his calves expand, his leggings become smoother and tighter, changing into Nike Pro tights, still showing off his huge bulge through them. Finally, his shoes expand with his feet to become size 12 bright blue Nike cleats. New memories enter the heads of the entire class, telling you all that the muscular man standing in front of you is a PE teacher who is covering your class because your normal teacher was off. He adjusts his now erect cock through his tights, the touch causing a dribble of precum to spurt out and stain them. He sits back down in his seat and smirks to himself, as you notice your own cock is completely hard, and you try to hide it before realising that nobody cares.