You hold up the five-minute penis potion and give her a look. She frowns.
"One last time?" she asks. "As close to human as we will ever be. One last time." She closes her eyes in resignation. "Let's do it. Let's do it out of hate and spite." She sighs. "You drink the first half, then I drink the second half. Then no matter how big you are, my body will accommodate you."
That was an unexpected twist. You are glad she knows how to use her own potions. You wonder what other potions there are and if they might also be fun or not. Quickly, before any more transforming can happen, you drink the first half of the potion and pass her the vial. She drinks it, similarly in a hurry, and then lays down on the floor, her pig legs parted and her still-human pussy primed after she had been so enjoying your transformation.
You feel a breathtaking sensation. You look down at your woman tummy and the woman hips below that, and watch your vulva push out into a massive cock. You reach your former size and smile with the familiar sensation of having male genitalia. Testicles drop, though they barely fit between your thick, fleshy thighs. But your penis continues to thicken, much like the rest of your body, and then to elongate. You don't feel the white hot of transformation, but the sensation is heavy and strong. Your new penis reaches a full foot in length, and thicker by three times than your penis had been when you were a man.
You look at the woman. Her pig legs are distracting, but you think of her big ass, untouched by the transformation, round and juicy, and your penis springs into action. You crawl up to her and sneer. She snarls back at you. "I hate you for what you've done. I despise you and I hope you turn into a goat."
You impale her forcefully. She clutches at the soft carpet and cranes her head back. You thrust again and again. You rest your huge hips on her and push, pinning her under your plump body and causing her to gasp. You hope it hurts. You move in and out, every thrust a stab with a knife. And as you move, you can feel yourself continuing to grow longer and thicker. She changes to match you. You grunt in anger. You wanted to be big enough to hurt her, but all your jamming is only serving to make her experience the thrill of sex. Human sex, one last time.
And as you plug her again and again, you feel your body melting into the white hot feeling, this time in your chest. Your penis is alight with excitement, and how the pleasure of transformation on top of it? You start to shudder, but you keep thrusting.