"OK, I am naked, now what?"
"As being born a muggle, you offer special properties to aid the class, they here to learn through demonstrating of their attained knowledge of spell-casting, making use of you as a model. Today we shall begin with simple physical altering, nothing of a permanent nature, but enhancing and endowing, making you look like a human becoming a donkey." The teacher so explains.
"No not a donkey!"
"Class, who wishes to begin, ah Miss Mun Tour, please do your best!" The teacher asks as chooses one of his favorite female witches to do what he knows will inspire and humiliate.
Miss Mun Tour raises her wand and pointing it at the shivering naked form of a young male human, she says, "Donkified genitals please!"
The spell cast the male model doubles over forward from the sudden surge of power engulfing his groin. Moaning as groaning, he expounds several grunting sounds what makes many of the class members there to laugh. The teacher is smiling as the model rises again to standing upright and down low being very erect.
"Oh, oh ah damn, oh, oh, ah..., will you look at me now, I got what Miss Mun Tour would like to suck on!" The muggle model said, he standing there with the fully erect male member of a mature donkey Jack. The donkified genitals are so huge, as testicles became like large oranges colored black, and from a sheath extended some twenty plus inches of black, blunt ended equine male meat, being fully aroused and dribbling of pre.
"No me Sir," said another student, she a bosom pal to Miss Mun Tour.
The model being red faced from disgrace and a heightened state of arousal, stands there using both hands to hold onto his changed male member.
"Miss Wilks, if you please, show us you ideals about being a donkey." The teacher chides the student as if to dare her.
Standing then beside her pal, Miss Wilks pointed her wand at the donkey model and said, "You stated you were a stud, to be a donkey Jack made for stud, you need the hind legs to stand tall enough to breed!"
Again a punch in the gut by the cast power striking the muggle-model and with a might cry from him of "Oh shit," his legs hunched, as muscles grew, changing his stance, making broader flanks, strong as narrowed buttocks, endowing the model with a donkey tail as heels became hocks, feet elongating, and toes were as hoofs, a muggle was half then a donkey.
"Me Sir," said Anthony, a wizard son of a grand wizard father, grandfather, and a demoness mother.
"Be careful young Anthony, you have too much of your mother in your casting ways!" The teacher warned.
Anthony stood up, as taking his wand in one hand and pointing it at the muggle model, he raised skyward his other hand and with a loped swirl of the wand he said, "Muggle donkey, is in need of some fur!"
Instantly the skin color of their muggle model changed from his natural dark tan hue to that of the common blacker hide of a dark furred donkey. As lowering his raised arm and pointing with his free hand, Anthony added, said, "Muggle Jack donkey feel the urge to breed!"
Sudden undeniable pangs of lust formed in the chest of one donkified muggle, as what was erect became rock hard stout.
As suddenly the classroom door opened and in walked an upper class monitor, as he approached the teacher, handing the man a note.
"Class dismissed, all must go to the meeting hall, except for Anthony. Mr. Anthony, I want you to take our model to the stables and let him get accustomed to his changed self, as tomorrow we shall finish what we started today. Oh and be sure he does not mate with any equines, as to mate makes his being a donkey as permanent, and I promised out muggle student he would not need be forever a donkey!"
At that the teacher cast a short spell and placed upon a donkified student a head halter with reins for leading him to the stables and a night of horror.