The drive to the supermarket lasted longer than she expected due to a construction detour. This only concerned Mary because her tail was in constant agony being sat upon inside her pants.
She entered the store and somehow found herself making a bee-line for the cheese section. She piled all sorts of varieties of cheese wheels, wedges and blocks into her cart. The only detour she made on her way to the checkout line was to stop for a couple cartons of milk.
Mary noticed as she pushed her cart along that her bra and her pants no longer seemed tight on her. Her tail was still cramped, of course. Before getting out of her car she tried to make it more comfortable by slipping it down her left pant leg, but as it had grown to eight inches, she feared someone might notice the lumpy shape under the fabric. But still, her waistline seemed to be a perfect fit for her pants once again. She hoped this didn't mean the effects of the gender vial were wearing off, but she couldn't help double-checking the size of her breasts and feeling behind her butt for the bottom of her hairline.
The cashier looked at the amount of dairy products in Mary's cart and raised an eyebrow.
"Cheese party," Mary said all-too-innocently. The cashier said nothing as he scanned the twenty or so items.
After loading up her car--and eating a few pre-diced squares of cheddar--Mary sat down carefully in the driver's seat. She made sure no one was near, then fumbled with the clasp on her pants. She snaked the waist down her thighs just enough to free her tail, allowing it a bit of room to move around in between her and the back of the seat. "I guess these cars just weren't designed for mice," she shrugged. As she turned on the ignition, she noticed her rear view mirror needed adjustment quite badly. "How did that happen?" she asked herself as she angled it further downward. It was like someone taller than her had taken the car out for a spin.
In fact, Mary guessed that's exactly what happened. She looked at her own reflection, then down at her body. That explained why her clothes seemed to fit her all of a sudden... She was shrinking!