You decide to take the gorilla mask, as you always wanted to monkey around wearing one of those. The craftmanship was impressive, sporting dense black fur, prominent and sharp canine teeth, and though leathery skin. It's so realistic, you could swear it was an actual gorilla head, albeit one scaled down to fit a human.
Without delay, you slip on the mask, adjusting the eyeholes so you can see perfectly, and walk towards the mirror. Looking at your reflection, you chuckle after seeing how nice the gorilla mask looks on you, making you seem both intimidating and silly. You make some poses, scratching your armpits and crunching, making grunting sounds to emulate a gorilla. You start making plans, you can't wait to wear it elsewhere and show it off, maybe taking it for a halloween costume contest... Or maybe just wear it around the house, embracing your inner primate self.
Without realizing, your own masked reflection starts getting you into a deep trance, making you more comfortable with your new gorilla face. In fact, you start to forget what you looked without the gorilla mask, making you unwilling to ever take the mask off. You look so manly with it on, why bother taking it off? You wish that the mask could become your new face, forever... and as soon as you had that thought, the edges of the mask fuse with your neck, as the skin of the mask starts to shift and contort, and the black fur of the mask becomes realistic and starts taking roots under your skin. You start feeling itchy, and as you scratch your neck, you notice that the black fur has already starting to spread far below your neck, covering your shoulders and heading towards your arms.
The eyeholes now spread and fuse with your eyelids, as your face is pulled and stretched to fit the shape of a gorilla's skull. Black fur continues to spread, covering your body little by little, while at the same time, your muscles expand and become ten times stronger than they were before. Your body is in so much pain by the transformation, that you pass out...
Couple hours later, you wake up with a start. As you look again in the mirror, you realize with horror that the transformation finished while you were unconscious. There's no longer signs of a mask, as now you are a big and strong male silverback gorilla, standing in front of the mirror. For some reason, your clothes stretched alongside your transformation, now fitting your larger frame. Your whole body is now covered in dense black fur, your hands and feet are now massive gorilla paws, your arms now have massive fur-covered biceps, and your belly has expanded into a big, round gut. From being a boring, common human, you have changed into a manly and muscular 6 ft tall gorilla. A very handsome and sexy looking gorilla, at that... wait, what?
As you contemplate your new furry form, you notice that your manhood has tripled it's size, now veiny and covered in a grey sheath, with a pair of gorilla balls holding your ape seed. As you stroke it with your gorilla paw, you feel your hairy organ hardening, sending a wave of pleasure that your primate mind cannot ignore, as you 'OOK' loudly in response. Unable to resist, you grab it with your paw and start masturbating to the image of yourself posing in the mirror.
Soon enough, your mind gets invaded by fantasies of male gorillas loudly pleasuring themselves, pleasuring you... But wait, weren't you straight? You were attracted to girls before... but the more you think about sweaty male gorillas and their thick and massive cocks, you get even harder, your blood boiling, and your gorilla balls aching for release. Soon enough you reach the climax, howling loudly as you release a thick jet of cum, staining your black fur and part of the ceiling, your whole body invaded by a pleasurable sensation you've never experienced before.
Regaining your breath, you stand your gay ass up and clean yourself off, being proud of the huge ammount of cum you have produced in one jerk off session. As you look in the mirror, you say to yourself "I'm a gorilla. I've always been a gorilla", as you notice that your voice now sounds deeper and gutural. Just to ensure this is not a dream, you grab the top of your head and pull to ensure it was real, but nothing budged. The mask has somehow fused with your head permanently transforming you into a gorilla.
Thinking on your strong and manly ape body is getting you horny once again, except this time you know jerking off is not going to be enough to calm your gorilla cock. You need another male to cum and satisfy your urges... someone to stick your 10 inches of gorilla meat into...