"How about you?" she asked.
"M-me?" you stammered.
"Yes, you." Ms. Tomlin repeated. "Come on up, don't be shy."
Nervously, you made your way up to the front of the room. "Now then, I'm going to need you to take a drink of this liquid." Ms. Tomlin explained.
"Why?" you asked.
"Oh, you'll see..." Ms. Tomlin replied. "Just leave some for the rest of the class."
Hesitantly, you grabbed the vial and took a swig of the liquid. You forced yourself to swallow the thick, milky substance.
"Now, how do you feel?" Ms. Tomlin asked.
"A little weird..." you answered.
Suddenly, you stumbled back before you fell on all fours, a wave of nausea falling over you.
You were about to say something, when you began to feel a tugging at your ears. Curious, you put a hand on one of them, only to realize they were growing longer! They soon grew huge and flopped over, as your nostrils started to flare out. They began to grow larger as your nose and jaw began to push out into a muzzle. You felt a poking at your forehead as two small horns forced themselves out of your head. Your fingers began to fuse and harden, as they reformed into hooves. Perhaps most shocking of all was when a painful feeling started in your crotch. You grabbed your manhood in pain, before you felt it slowly retract into your body, leaving a female flatness behind.
"Wh-what's happening to mooo?" was all you were able to sputter before more pain began. Your entire body became covered in thick white fur with black splotches. Your entire body began to gain mass until your shirt was torn off. Your toes began to merge until your feet had become a pair of back hooves, tearing off your shoes. Your stomach began to churn, expanding and rearranging itself as you sprouted several rows of breasts. Your butt and hips began to inflate to inhuman proportions, stretching your pants at the seams. Soon, a short tail had sprouted from a hole in your pants. A huge pain started to form between your legs, until a huge, pink organ was growing from your body, destroying your pants. You wanted to scream as you felt teats full of milk begin to push out from your new udder, but all that came out was a loud moo.
Soon, standing at the front of the class was not a regular human teenage boy, but rather a female dairy cow. The entire class stared in shock and awe.
"Well, you certainly turned out nicely!" Ms. Tomlin beamed. You wanted nothing more than to curse her out right then and there, but all that came out was moos.
"Why don't you go stand in the back of the class for the time being?" she asked. Seeing as you had no choice, you reluctantly obliged. A few students giggled, and you tried to resist the urge to trample one of them.