A request by Admiral Biscuit:
A pony (or whatever) comes to Ponyville and talks up all the useful applications of her new invention.
That invention is fire.
“Step right up, step right up!” Flim called, telekinetically whirling a cane beside him in that way only unicorns can. “See the technological marvel that’s going to change the face of Equestria forever. It prepares food, warms the home on cold days, provides light where before there was only darkness.”
Flam tipped his had to the crowd, picking up where his brother left off. “And it has industrial applications too. Stare in amazement as mortal ponies shape metal, prepare charcoal, and use our marvelous creation to produce a hundred other products that will change your lives forever!”
The mane six sat, stood, and hovered a few dozen yards from Flim and Flam’s tent, their expressions each some variation on the core concept of “befuddlement.”
There was a banner over the tent, advertising the abstract concept of fire with the tagline: “It’s Catching!”
“This…” Rarity gestured vaguely in the tents direction, her mouth pulled down into a tight frown. “This is some sort of prank, yes? A performance art show?”
“If so, they’ve got a lot of… what’s the term? Ringers?” Applejack gestured at the line of excited ponies waiting outside Flim and Flam’s tent, eager to see this marvelous new creation. “Too many. I know some of those ponies.”
“Maybe they’re all, um…” Fluttershy hesitated. “Beguiled? Charmed? Mind controlled? Has anypony seen Starlight today?”
“She promised not to do that anymore.”
“Twilight I would never speak badly of your friends…” Fluttershy began.
“Nah. They’re not brain-whammied,” Pinkie shook her head. “Look at them, they’re chatting in line, joking with their friends. Not a glassy-eyed stare among them! Except for one-eyed Pony Pete and his glassy eye of course.”
“Screw it,” Rainbow shook herself out. “I’m going to go see what’s in there.” Without waiting for the rest of the group, she darted ahead, flying over the line and straight in through the flap of the tent.
A tense moment passed. Flim, Flam, and Rainbow’s friends alike all stared at the tent flap through which she had vanished.
With a scream, Rainbow Dash shot back out of the tent wreathed in flames, her mane, tail, and feathers all combusting before their eyes. “Fire, fire!” she screamed, shooting off into town and crashing into the nearest horse trough. She desperately hurled herself into the water, trying to extinguish the flames.
Quick on the draw, Flim lifted his cane to the sky: “Another satisfied customer!” The ponies in line burst into a round of spontaneous applause.
“But,” Twilight exclaimed, “that only raises further questions!”