An audio of a robot girl transforming into part-cow, commissioned by  Quackington
Here's how the story goes down in this audio:

“Excuse me miss. Would you like a sample?” A small robot stands behind a poorly crafted demonstration table bearing the name “Heart Milk.” The robot bears none of the human-looking features Roll and her brother possess, instead looking metallic and emotionless. It wears a cheap suit with a faded nametag.
“Oh, me?” Roll responds.
“Yes little girl. Please come try our milk.” The robot enthusiastically holds up one of the clear bottles.
“Ummm sure! I have some extra time.” Roll responds. She is not one to judge by appearances but is hesitant nonetheless. Her trusting nature gets the better of her. She approaches the stand as the vendor describes his product.
“Fantastic, here take this.” The robot hands Roll a small clear bottle. “Heart Milk is a specially engineered product that, believe it or not, doesn’t come from cows. N-now before you doubt me give it a try and tell me that doesn’t taste just like regular milk.”
Roll eyes the robot curiously before raising the bottle to her lips. She slowly swallows it and is amazed by the taste. Not only does it taste exactly like a cow’s milk, but it is the sweetest and most flavorful milk she has ever tasted. She savors the rest of the bottle and when it is through catches her breath. The vendor laughs quietly.
“Oh wow! That was incredible. What is it made of?!” Roll exclaims as she turns the bottle in her hand looking for its contents. When she finds none she turns her attention to the vendor who has vanished. In his place momentarily is the vertical beam of light indicating that a transportation device had been used on him. The robot took the other bottles of Heart Milk with him and Roll now stands alone before the empty stand. “Well that was … odd.” She notes. As she turns to leave a sudden pain in her stomach causes her to pause.
Roll sets her paper bag down on the empty stand and holds her chest. Her digestion system is rumbling and she feels unfamiliar signals spreading throughout her body.
“Oof, what –was- in that milk?” She groans.
Roll begins to feel a tingling at the base of her back. She brings her hands to the spot, but finds nothing unusual. Then all at once something protrudes outward. It grows and grows as Roll yelps in surprise.
When it is through growing Roll inspects it and finds that it is a white and black tail of about eight inches in length with a tuft of black fur at its tip. It peeks out from under her red dress. Panicked Roll grabs the tail and tugs.
“Youch!” She shouts. “W-what is this?”
Roll has little time to ponder the development as the grumbling of her insides grows more intense.
Feeling embarrassed she sidles into the shaded alley and leans against the wall of the grocery store.
“What is happening to me?!” She cries.
Roll is holding her stomach when it begins to expand. From her torso it slowly droops and balloons. It quickly fills her undershirt and Roll spies four raised bumps. All at once the bumps tear through her white undershirt to reveal four growing teats. These are followed by the pink, swelling mass of her rapidly forming udder. She holds it tightly wishing she could pull it back into herself and undo the transformation. She is startled by how large it is. When she feels the growing subside she stands straight to inspect the tender pink thing.
“An udder?! The milk! But why would he do this?” Roll frantically tried to imagine what would cause a robot to trick her into ingesting the spiked product. She looks at the soft pink udder bulging out from under her red dress. “Oh no, how am I going to get home? I can’t hide this big thing.” She whispers. The image of her ‘father’ and brother terrified of her new changes creeps into her mind. “Ohhh, they’ll think I’m a freak. No, no. I just need to get home to Doctor Light. He’ll know what to do. But first...Let me just check myself out. This isn't so bad afterall. Cute look...Teehee.”

Story/Script by  SnakeMole (Except the very last bit about her checking herself out, that part of the script was done by me )
Thumbnail image by  FeiOna
Roll character belongs to CapCom.
All voices and audio done by me.
Sound effects from Pond5 and SoundDog.