Once Russia was a pancake, trampled by dozens of shuffling canyons sculpted by her lovely "petite" feet, Andrea stood in the thin puddle of the ocean and waited. She stared at her hands, frowning, wondering if perhaps she'd been mistaken in her understanding of the growth process. She didn't have to wait long, though.
Abruptly, the already-shallow ocean, which even at its deepest point only rose above Andrea's ankles, seemed to drain lower, or rather, the girl herself was stretching yet higher past the stratosphere and into outer space itself. Now that the ocean couldn't even fully contain her foot, running in rivulets down the sides and spilling between her toes, Andrea could make a pretty good guess about her success, based on the height of the water and the dwindling appearance of the country she'd just finished ravaging, now stamped by footprints which comparatively looked like a child's next to Andrea's. She had doubled in size, if not more, and she wasn't even finished growing.
"Well," she laughed. "I guess that worked!"
Her body continued soaring higher, expanding in perfect proportion, and in some ways became even more flattering. The girl's figure turned curvier, her buxom bust swelling to the size of small moons, while her athletically toned rear end could've cracked the whole planet if she sat down hard enough. Andrea, surprised yet pleased at these additional benefits, admired herself in the still waters of the ocean like a mirror, turning around into modeling poses and marveling at how desirable her figure had become. It was true what she'd said to the pitiful little microbe-people below: she was becoming more beautiful, and only getting more exquisite with each mile of height she gained. She decided it would only be fair for humanity to enjoy the dazzling visage of their destroyer just before she made short work of their vulnerable globe, as a final parting gift.
Andrea walked in steadfast circles around the Earth. The taller and stronger she became, the faster she moved. Entire bodies of water splashed across the crumbling remnants of shoreline countries, drowning most of the populace, and leaving the rest to float helplessly in the tsunami-grade puddle just before Andrea's foot came colliding through the clouds to drive them into the briny depths. As she bypassed three hundred miles tall, then four hundred and even higher, Andrea delighted in how much more efficiently she could quash the world below her heels like gingerbread. Before her last growth spurt, it took multiple curb-stomps to down just one major capital, but now, even the most expansive and architecturally sprawling metropolises met their end in just one step. Some that were located closer together could even be stamped to dust in the same footfall, two or three at a time.
The giantess focused on the various sensations the destruction of each country brought, enjoying each one uniquely. Natural lush green locations were the most pleasant to step upon, as lakes and forestry alike tingled like soft feathers on the plush undersides of her feet, even tempting the semi-erogenous zones between her digits. Thickly populated man-made cityscapes, bright and silvery and full of one-time promise, were more amusing, as it felt like breaking intricate sugar crystals with her feet, though these too offered no rebellion to the relentless rise and descent of her peds. The mountainous locales were the toughest to bring down, but with a roll of her toes or a pile-drive from her heel, even these hardy bits of pointed topography were leveled off into a flat, lifeless plain in the exact shape of Andrea's continually evolving feet.
In no time, she was crushing whole countries in one step, and then even this seemed like a small feat, when Andrea found she could practically pick up an entire nation by wedging its jagged tectonic border between her bulbed big toe and slender second toe, clamping them together, and lifting the country up like a dinner plate. This turned into a fun diversion for the giant eighteen-year-old as she crested a height well-past one thousand miles and climbing. Andrea alternated between trying to delicately pick up the countries in one piece between her toes and flinging them around the orbit, or simply letting them come apart in brittle chunks when she'd crunch her strong, sun-kissed toes together. Clumps of country plunked into the water below from Andrea's magnificent airborne foot, though just as much of the mushy land-debris became lodged like clay into the tender toe-crevasses and the dimpled ravine-length creases of Andrea's heavenly soles.
Gravity no longer held Andrea earthbound; she was large enough now to make her own gravity. She took advantage of this by letting herself drift peacefully in the space surrounding Earth, as her height had become incalculable in miles, but it was more than enough for the girl to notice that she was now taller than the diameter of the entire Earth by a sizable amount, and still continuing to swell. Her chocolate-brown hair fashionably spread out among the cosmos, as though she was floating underwater; her arms lay at her sides. Only the girl's toes remained in consistent contact with the shell of Earth.
No longer even able to pick up individual countries in her digits without instantly smashing them like pollen clusters, Andrea adapted instead to scooping up the continents one by one between her ten dancing toes, or at least as much of them as she could grab. These broken shards of Pangea were so fragile now, that even the deepest roots to the center of the planet by the center of a continent could do nothing to resist the insistent, greedy pull of those lovely, pinkish, pedicured toes. One at a time, Andrea wasted each location, grinding them to dirty pulp in the arch-canyon of pale, beefy skin between each monumental toe; she saved her home continent for last, and savored its decimation for the longest, then extended her leg far from Earth, letting the grit of North America sprinkle out from between her balletically flexed toes and disappear amongst the stars.
Her ultimate farewell to the planet was not yet finished, though, and once Andrea had outgrown it enough that she couldn't even attempt to keep a balance on the marble-sized thing, she cupped the Earth between both soles of her inward-facing bare feet. She let it tumble among her arches, massaging her hard-working flesh, then let it come to rest between her fateful toes. Smiling at her accomplishments, and waving goodbye to any of the few remaining humans left intact, the globe disappeared to darkness between the pillars of Andrea's toes, which pulsed together only once, as that was all that was necessary to render Earth just as broken and insignificant to her as the rest of the tiny universe she had yet to conquer underfoot.