You get tricked alright.

You head down to the head of the class, not exactly confidently, but not entirely cowering either. Professor Cambio looks you over as if you were a piece of meat. "Alright, Mr. Robertson, you were the most attentive, so hopefully that means you are a diligent student. Take off your clothes and assume a humanoid form."

You feel the eyes of all your peers in front of you, worried you will embarrass yourself if you can't "firm up" under pressure. You aren't sure how basic a skill this is for full slimes, and you hope you won't be the lowest of the lowest level monsters due to being half human. You slowly unbutton your shirt, taking the time to remind yourself you have already done this once, and with a huge cock threatening you to boot. Your body goes slack as your shirt falls to the floor and you hear your classmates laughter as you start to slump backwards towards the floor.

You imagine yourself flexing muscles you don't have and lifting yourself into a standing position. You focus on pulling yourself up and block out the jeers and titters of your fellow students. Slowly...agonizingly you rise to a standing posture, and begin to take on blocky human features like a featureless head and arms with simple hands. You strain to your fullest and begin to take on your boyish, slightly androgynous features including thick strands of slime hair and body definition. Your "skin" firms to a thin solid membrane, allowing you to pull off your pants, which you step out of with two fully formed legs, and a big swinging dick you never had as a human, but you don't see any reason to let anyone know that. The laughter has stopped and replaced by mumbled recognition of your efforts.

"Now this is interesting class. You can see by his...ahem...milky complexion, that Mr. Robertson is a half human slime. But what he lacks in experience, he clearly makes up in willpower. I find humans to be a frustratingly willful race, but they are also easily distracted." Professor Cambio illustrates his point my gripping your chest and pinching out two pert but perky breasts with lovingly detailed nipples. You are amazed at his artistry and his swift speed. You are mesmerized as his hands slide down your body and deftly squish in your waist and push down the extra slime to give you an ample ass and full hips.

You blush and it lends an appealing glow to your milky, shiny body. You feel yourself melting in his expert hands, finding it hard to focus, not sure you even want to stop him. It's only when he pulls your cock off with a wet PLOP and starts forming a wet, wanting slit to replace it that you shout, "Stop it!"

Professor Cambio smiles gently before sliding your still firm, fat faux cock up inside your new pussy. You try to stifle a moan as he slowly stretches you with your own prick, but you can feel every inch of your cunt caressing your cock, which still somehow has supernatural sensation. Even more troubling, your pussy feels even more sensitive than your prick, and it's all you can do to hold yourself together. You desperately whimper, "puh puh MOAN please AAH...stop OOH...it NNH...it WHIMPER...feels...so...OOOOOOH"

The class is no longer cheering, they're all too enraptured by the sight of you fucking yourself into a moaning mess. The Professor, clearly unconcerned about your humiliation or dignity, continues slowly fucking you while looking over your shoulder to address the class. "Now it's only a matter of time before this happens to you. Odds are, it already has. But the real measure of a slime isn't how they get molded or molested or mashed. It's how they FIRM up. Mr. Robertson was able to form a human, male form just minutes ago. The only thing preventing him from doing so again, is his lack of focus. So the question is, what kind of slime is he?"

You wonder yourself. Fucking yourself feels so good that you can't think of anything else. Why keep fighting it when the most you can hope for is to be the best of the worst. Why not just be the sluttiest of the slimes? Then again, Professor Cambio doesn't look weak, he found a way to FIRM up...maybe you can do?