"Well, I can fix that," Mary said. She had a feeling the udder was becoming more trouble than it was worth. Though she enjoyed the sensation of its warmth and pressure, she couldn't let it ruin a possible relationship with a man she admired. Mary excused herself to the bathroom and opened up her purse.
She rummaged around for the human vial, took it out and swallowed a good quarter of the potion.
With her other hand, she lifted up her sweater in time to see her udder shrinking. She took another few sips and it had gone completely, teats retreating into the skin, leaving her with a perfectly normal stomach.
She capped the vial, zipped up her purse and rejoined the party. It didn't take long to find a few more friends, and soon they were exchanging stories about old dates, their boss and how ridiculous the people across the room dancing to the music looked.
However, after several minutes of blending in, Mary suddenly began to feel the familiar bloated sensation. Trying very hard not to panic, she held her stomach and attempted to stand as straight as possible. "Ooh," she half-moaned. "I'm sorry, I think I need to use the bathroom."
As she quickly staggered away, she heard one of her friends giggling about "too much punch." Making it into the bathroom, she closed and locked the door.
Once again the pressure returned, even more painful than before. Her belly gurgled loudly, and Mary could feel it swelling once again under her sweater. She hugged herself tight, reeling from the flood of her udder's expansion. Then she felt something that hadn't happened before. A pain at the base of her spine made her suffering even worse. Finally, her udder had swelled to its original size, complete with six four-inch teats. Mary regained her composure, no longer in pain, feeling the familiar sensation of the warm milk inside of her.
She looked at it in the mirror, scowling. The pink hump stood there, dangling off of her stomach and straining as it rested atop her pants' waist. Then something else caught her eye. Something moving behind her.
She turned her head and discovered that, in addition to her udder, she had re-grown her tail. The black-and-white furred tail, ending with a thick tuft the same color as Mary's hair, idly dangled to below her knees. It had torn a hole through the thin fabric of her casual pants. Clutching it in disbelief, Mary fearfully wondered if there was some strange side-effect to the vials. Twice she had tried to return to normal, but twice had her cow traits resurfaced.