Rob hears Mary's groans from behind her massive bowine udder.
"I think it's- oh... it's starting again." she cries, pinned down by the weight of the milk sloshing around inside.
Her udder quivers and picks up growing where it left off, growing butting up against the ceiling and the walls of the room in the house. A slight crack was heard as the drywall began to give way to let the mound of flesh thru. The ceiling also began to crack rubbing Mary's very sensative udder, making her moan in both pleasure and pain.
Rob, as of this point, was backing towards the door as Mary's udder grew and grew and grew, like a milk filled parade balloon swelling up. The house didn't look like it would have much hold left on it. The windows of the front of the house burst as Mary's udder hit the far wall, Rob bolted for the door and stood in the lawn, looking back at the house.
It was like a seeing a bird hatch from an eggshell, as Mary's pink udder split the house in two, raising the top half of it until it fell behind as a pile of broken wood, furniture and brick. And still her udder grew. The remains of the first floor were leveled as the udder was now larger than a mansion. Finally the large pink balloon stopped expanding and Rob could hear a faint moaning coming from Mary somewhere behind it all.