The vault had always been quiet, just the hum of machinery and the occasional clank of metal. You and your companion wandered into the storage room, spotting a crate labeled “Experimental Nuka-Cola: Mutant Moo Edition.” Curiosity—or vault boredom—won.

“Should we?” your friend asked, dark hair falling over her shoulder, eyes sparkling with mischief.

“Absolutely,” you replied. The two of you popped open the bottles simultaneously. The fizz hissed strangely, glowing faintly green. One sip. Two sips. Then… a warm, tingling sensation spread from your stomach outward.

You laughed nervously. “Uh… my stomach feels… weird.”

Your friend touched her belly and gasped. Both of your stomachs swelled rapidly, soft and round, expanding until your clothes stretched tight. Then your breasts followed, growing heavier, fuller, impossibly full in a way that defied reason.

A low, strange sound escaped your throats—more than a laugh, more than a moan. Your ears itched… and then grew, curling into soft bovine tips. Horns sprouted slowly, small at first, then curving elegantly above your heads. Your tails flicked involuntarily, knocking over a stack of Nuka-Cola crates.

“What… are we becoming?” your companion whispered, wide-eyed.

“Moo… I think we’re… part cow,” you said, voice trembling as a small stream of milk leaked from your suddenly sensitive breasts. Both of you stared, then shrugged, realizing panic was useless.

The rest of the vault seemed distant. All that mattered was the warm weight of your expanding bellies, the soft tug of your new tails, and the odd satisfaction of being… utterly transformed. You laughed together, the sound half human, half bovine, as you adjusted to your new forms and the milk continued to flow with an almost comical consistency.

By the time the glow faded, you were no longer just vault dwellers—you were vault cows, fully embracing the absurdity of post-apocalyptic mutation.