"That is not very nice, young man. I think you need to revisit your manners." The teacher smiled. "And some time to improve your attitude."
The young jock started to reply, but gasped as his clothing disappeared, revealing his trim, muscular body and a moderately decent circumcised genital package.
"First, we'll give you time." The teacher waved his wand and said 'Regresso Pubicicus!" A flicker of blue light shot around the startled jock as he shrank suddenly into a 13 year-old version of himself. Still handsome, but missing the muscle that a few years of athletics and growth would bring. He stared at himself and said in a higher voice "You can't do that! This is impossible! I'm not a kid!"
"Ah, but you are. And since you have been rude to my students, not a very handsome one. Homelicus Nerdicus." The class laughed as the young teen got thinner, shorter, and ugly. His teeth bucked out large and crooked, his hair got shaggy and dull brown, his eyes turned a washed-out blue, and his ears stuck out. Then his forehead dropped and his brow thickened. He was now a little freakish himself, a Neanderthal in modern times. He stared down at his skinny, oddly proportioned body in horror. "No! Please! I'm sorry!"
"Well, since you said please, I'll give you something to be proud of." The teacher waved his wand and said "Hungus Horsicus." The scrawny cave boy's genitals suddenly swelled out and change into those of a stallion, complete with sheath. They were ridiculously big on the 13 year-old, the black shaft dangling past his knees. "And now let's make it all work."
"Adjustus Realitious." The boy's frantic and terrified protests suddenly stopped and he scratched himself absently as he looked around the classroom. The teacher smiled at the class. "Our rude young friend is now a horse-hung cave boy. He has no concepts of clothing, no memory of being his former self, and the IQ of a gorilla. What shall we do with him now?"