Carrie felt the ray wash over here and a tingle went from the top of her pointed ears down to the tip of her big thumpy tail, "This feel REALLY good, John!"
With that the sales clerk let go of the trigger and the light dissipated from the growth gun and the feeling went away from Carrie's being.
Carrie saw she was still the same height, "Now what?" she asked the clerk.
"Just wait... 5. 4. 3. 2..."
With that Carrie's feet grew to fantastic sizes. They went from a toonish 3 feet long kangaroo paws to being 4 times the size of her body! Her flufffy digits, knocking over racks of costumes and pressing her husband and the sales clerk against the wall of the establishment.
The growth didn't end there. It continued from her feet up to her body, which was quickly catching up in scale, but not proportionately. First her ears grew giant, then her tail, then her muzzle got quite large, leaving her quite a sight to see. This only lasted a little though as the rest of the parts grew too, leaving her a proportionally sized abet giant kangaroo woman pressed tightly in the building, filling up every corner of it.
"I said I only wanted to be a FEW INCHES taller!" she boomed down at the clerk.
"You can't blame me for this. You ask to be taller!"
Carrie felt herself press tighter against the roof and walls of the building, she was starting to grow again, she realized.
From the outside of the costume shop, it would have looked like someone over-inflated the building as it stretched and contorted to fit the growing marsupial inside. Finally, with a creek and a bash, the building finally gave out as Carrie outgrew the building, bursting it like a balloon. And even then, her growth didn't stop. Her growing paws pressed against the cafe on the other side of the street and many of the toon and human patrons went running. The giant roo lady's paws, were the size of a city bus by this point, no wait, two buses.
Standing up, Carrie assessed the damage, the costume shop was ruined and the city streets were forming massize cracks in it as she put on more and more weight, already in the several tons as she grew larger and larger.
Peeking thru the rubble, she found her husband, who thankfully was uninjured. Delicately grabbing him in her fuzzy hand she realized that he is barely half the height of one of her fingers now. She held him up to her face, "Well John, I guess I'm a bit taller now."
John gazed at the skyscraper beauty in the eyes, which John realized were now larger than himself now. "What are we supposed to do now?"
Carrie thought, "I suppose I could-"
With that there was a honking coming down from below as a toe-sized taxi cab driven by an angry looking wolf yelled up at the traffic blocking 500 foot tall roo. Carrie effortlessly picked up the taxi and flicked it away like one would a small bug until it made a ding as it disappeared into the distance.
"-as I was saying. I suppose I put you on my head and you can ride there until this is sorted out or I could put you in my pouch and Carrie you there."