Lyra shouted, "Oh, ah, oh, my breasts!" and tried to clutch her chest. It didn't stop what was happening to her. Both of her boobs, and the hands that were trying to hold them in place, sank lower and lower down her abdomen until they were resting on her groin. "Ah! Why are they down there?!" she asked. But you had no answer. All you had were a pair of male nipples tingling and feeling lower and lower on your own body. You gasped and even moaned when your nipples came to a rest on the sides of your penis! Was this where male donkeys had theirs?!
Lyra groaned and reached for her vulva which was darkening and swelling. But it was moving too. It got closer to her anus, which got closer to her tail. As for you, you were looking down at your own crotch, staring in awe at your foreskin's steady fusion with your groin skin. Then it started to grow, as did your balls. It looked like you had a big round tube attached to you your belly with a not-much-thinner tube inside it. Your mind was screaming at you not to touch it, not to acknowledge that you were a donkey down there now. But your hands, driven by some primal need to know the way you worked down there, began rubbing what was now a very bestial sheath. What dropped out of it was decidedly unlike the human dick you had been using all your life. As more and more of its jet-black length emerged from the sheath, it was clear that the full size of this thing could easily dangle down beneath your equine hocks, maybe even almost to the ground had you been standing up.
"No, not my penis," you said with your voice. Granted, you knew many a guy would love to have a massive dick. You always thought you would. Lots of guys brag about having one whether it's true or not. But this, this was literally inhuman!
But it was yours now, and if Dr. O'Tanner was telling the truth, it would always be yours. From now until the rest of your days, you were going to have to feel. To use it. To understand it. So your curious hands moved from your sheath to what was dangling out of it. And as they they lifted up the heavy feet (not inches, FEET!) of donkey dick in front of you, they tried holding it in different ways, so you could get a feel for what it meant to be "hung like a horse" for real.
Your sexually confused mind remembered you were not alone, so you quickly turned your eyes to check on Lyra. Funnily enough, you still didn't immediately let go of your donkey dick. But you were somewhat concerned what she might think about you seemingly masturbating at a time like this. You needn't have worried. She was completely ignoring you. Her eyes were firmly on her own groin. She was fondling and poking around on her newly minted equine udder, as morbidly curious about her own new anatomy as you were about yours.
So, naturally you took this opportunity to get a better look at what you might have to piss and cum through from now on. One of the first thing's you'd noticed was that thick, bulging veins ran all the way along it. Another thing you were starting to realize is that the head actually looked a bit different. It seemed to be a lot flatter in the front than your human cock head. As you kept experimenting and it got more erect, it eventually started to get wider, and you had to admit you were getting more aroused. You began to work your penis more aggressively, and before you knew it, its swollen head had flared around the edges into a bell shape, and finally you felt the pounding muscle spasms of orgasm kicking in. Your huge penis twitched, your guts tensed, your tail flagged side to side. And you felt the first pulse of semen you would feel through this equine shaft. All the way up your erect length, as far up as your chest, the fluid surged, before exploding from your wide urethra onto the dirt ahead of you. Another surge quickly followed. Your eyes rolled back in your head.
By the time it was all over, you had dropped your penis which was stretched out along the ground in front of you from your seated position. It was limp but still dripping some of your seed. And then it finally, gradually started slithering its way back into the protrective pouch it had extended from.
"Whoa, is that your dick now?" asked Lyra. She had finally let go of herself and stood unsteadily on her donkey hind legs, and she was lumbering towards you. She stopped one of the thick, chunky piles of semen you had sprayed and raised her lips in the flehmen gesture you had used to sniff her urine earlier. "Wow, that's, that's very manly," she said. You were flattered but also a little freaked out. Here she was complimenting a dick and sperm that did not even belong to a human being. But at the same time, she was also flattering you, and had even had sex with you earlier. You weren't entirely sure how to feel, but you thought, "Hm, she likes my masculine odor, does she?"
"What about if I do this?" you ask, and raise yourself to your own hooves. You haven't been to a toilet either since the party. You relax your bladder and almost startle yourself with the hard, fast surge of fluid that erupts. But now that your urine is on the ground, Lyra is taking in The Scent. "Did I ever tell you how sexy you are?" she asked. You grinned.