Image imported from derpibooru 
Original Description:
 
One day, Sandbar discovered a strange mirror. He stepped into it … and found himself turned into a strange-looking creature. His hooves were now replaced with hands and feet. And each hand had five fingers, and each foot had five toes! Sandbar recalled Twilight’s friendship adventures with Sunset Shimmer. He remembered her saying something about “humans”.
 
Little did Sandbar know it, but he had found his way into our universe – and was standing on our planet! Before long, he discovered that this dimension was much smaller than that of his own world!
 
Sandbar was so tall that his head reached above the high clouds! His feet were so massive – he could crush the downtowns of major cities with a single stomp! Great mountains would crumble like sand under his feet. In all, he was about 14 miles tall!
 
As it so happened, Sandbar had been teleported to the northern edge of the Northeast megalopolis. He saw the masses of buildings piled up along the coast – like sand on a beach! He thought, these human cities were a great beach for him to take a stroll. And the buildings would be like sand and gravel between his toes!
 
Before he started crushing cities, Sandbar checked under his feet – just to be sure there was no pile of dead bodies. When he saw (with his special magnifying glass from Twilight) that no one was really hurt, he realized that cartoon physics were at play. He concluded that this world would magically repair itself – as parts of Equestria have done multiple times. Convinced he was acting no worse than Celestia, he started playing with the tiny cities.
 
As he strolled down the East Coast, Sandbar stomped on all the major landmarks, excluding the most important parts of Washington, DC. He spent an hour napping on New York City. Sandbar thought NYC had the best “sand” of all – with plenty of buildings for sandcastles as well! Sandbar always loved sand between his toes – and having it in the form of cities to grind to dust gave him a very satisfying sense of power.
 
As Sandbar left the megalopolis, he found a lot more of the natural environment along the coast. In Florida, he saw what looked like another megalopolis – but in much more harmony with nature – with large parts of nature as part of the suburbs! Of course, Sandbar made sure to stomp on Jacksonville, Fort Lauderdale, and Miami. When Sandbar reached the Florida Keys, he decided to take another nap, lying in the bay between the Keys and the southern tip of the mainland. The water was like a thin puddle to him, but he loved the “fine mud” between his toes.
 
Afterward, Sandbar stomped his feet to give the Keys a nice friendly splash! Like a storm surge on steroids, the towns were wiped clean off the map. Walking back up the coast, he returned to where he was first dropped onto Earth. On a hunch, Sandbar called for the portal to reappear – and it did! From there, Sandbar hopped back through and returned home.
 
Sandbar was pretty tired after that “little” journey. He sat on his bed to relax. That was when he noticed … he was still an anthro pony! And he still felt some stuff between his toes. Looking under his feet, he found that he had brought some big souvenirs from his trip to Earth. A bunch of skyscrapers had managed to stay trapped between his toes, mostly intact! Landmarks included the Empire State Building, the Statue of Liberty, the Washington Monument, and parts of Boston, Philadelphia, Jacksonville, Miami, Jersey City, and Baltimore. There were also various other buildings crumbled and flattened between his toes and under his feet.
 
Sandbar thought, Yona would love to hear about his journey. And she would love the big little souvenirs that his feet picked up! Once the earth magically reset itself, he would love to take her along to the new world he had discovered. Yona would love smashing little cities – that was for certain!
 

 
Sketch by jerberjer. Slightly edited by me.