Sitting amongst the ruins of your pants you stare down in disbelief at the unmistably equine equipment between your legs. It still pulses, slowly growing as it sends shivers of pleasure up and down your spine. Despite having only just cum you already feel your balls starting to ache as they swell with fresh cum.
Looking up you see your girlfriend red faced with embarassment, her eyes fixated on your new equipment. "Wh.. wha.. what the hell happened to your...." she stammered, "is that a horses...?" she trailed off. Seeing her you feel your balls tighten and an animalistic lust start to take hold in you.
You try to stand but a new surge of pleasure overwhelms you and you fall back as you buck your hips, you penis stretching to a full nine inchs. Fur starts to cover your legs and you lose most of the sensation in your feet as they harden into hooves. "Babe!" your girlfriend cries as she scrambles over to you, snapped out of her shocked staring by this new wave of changes.
As your body's transformation slows and your awareness returns once more you look up to see your girlfriend crouched over you, wide eyed and her nose wrinkled at a strong smell. "Ughh, god! that stinks..." she whines and you realise you must have cum again, only this time the cum isn't on the grass, it's all down the front of your girlfriend's pants.