You're burning em', squirt.
Rainbow Dash inhaled, smiling as the cool evening air filled her lungs. She loved the sweet scents of the forest; it was one of the reasons she was always down to go camping. That, and it made her feel like a responsible adult as she watched the CMC run around and helped them set up camp.
So naturally, when they'd practically begged her to take them camping again, Dash immediately caved. She was hovering just below the treetops, admiring the results of a hard hour-or-so's work. They'd just finished setting up the tent, there was logs in the fire, and now Apple Bloom and Sweetie Belle were chasing each other around in some game. The sun was setting, so soon it would be time for her favorite part-- Camp fire stories!
Speaking of campfires, Dash's magenta eyes landed on Scootaloo, who was currently making smores. Rainbow Dash watched her impale a marshmallow on a stick, then stick it into the fire and wait. And wait. And wait... Dash frowned, the marshmallow had blackened at this point, and Scootaloo still hadn't pulled it away.
Okay, clearly nopony's taught her how to make S'mores. she thought to herself, fluttering downward to help out.
"Hey squirt!" Dash said as she touched down next to the campfire.
Scootaloo looked up, her eyes twinkling as a big smile stretched across her face. "Hey Dash! Thanks again for taking us, I'm having so much fun!"
"No problem, again," Dash said as she took a seat across from Scootaloo.
She had finally removed the thoroughly burnt marshmallow from the fire, plopping it between two graham crackers and closing it with a gooey chocolaty squish. Rainbow Dash grimaced as Scootaloo shoved the whole thing into her mouth, the smell of burnt sugar wafting over and tickling her nostrils.
"Erm, squirt?" Dash said, watching as Scootalo shoved another marshmallow into the fire.
"Yeah, Dash?"
"Let me see that, I gotta show you somethin'."
Scootaloo looked confused, but she hoofed the stick over to Dash.
"Okay, now watch me carefully," Dash stuck the marshmallow back into the fire, and after a couple of seconds she pulled it away. "See, you only keep it in there for about thirty seconds, then you pull it out. You gotta count the seconds, not just leave it in there, and now it's a nice crispy brown," she showed Scootaloo the perfectly toasted marshmallow.
"Um, okay?" Scootaloo said, watching as Dash used her marshmallow to make herself a S'more.
"Now you try it," Rainbow Dash said, munching on her newly crafted S'more.
Scootaloo grabbed a marshmallow from the bag, stuck it on the tip of the stick, then held the stick in the fire. Rainbow Dash counted the seconds in her head, her wings started to twitch as the time approached thirty seconds. She held her breath, then puffed her cheeks out, then she bit her tongue.
"Scoots," Dash finally sighed.
"What?" Scootaloo asked, still holding the marshmallow in the fire long after it'd started to brown.
"Y'gotta take it out now, thirty seconds have passed," was she not clear enough in her explanation? Did Scootaloo not know how long a second was? Rainbow Dash had certainly struggled with that as a foal, except she'd had the exact opposite problem where she'd thought that a second was way shorter. Now that had been hard to unlearn.
"But it's not done yet!" Scootaloo said, using her other hoof to point to the blackening marshmallow.
Rainbow Dash deadpanned. "Scootaloo, it's very, very done!"
Scootaloo glared and Rainbow softly, then after a moment of awkward silence she removed the marshmallow. Rainbow Dash shook her head, it must be the seconds thing!
"Scoots, do you know how long a second is?" Rainbow Dash asked, pawing at the ground nervously.
"Yeah?" Scootaloo answered, tilting her head in confusion.
"I'm sure Cheerilee taught you this in school,"--if she didn't, Dash was going to have a very strong word with her.--"But basically, the easiest way to count to a second is to say; One--thousand--Two--thousand--Three--Thousand--"
"--Rainbow Dash," it was Scootaloo's turn to deadpan." I know how to count a second, I'm your little sis, remember? You literally had me time your speed before!" she emphasized her words by raising her hooves in the air, a finished S'more in one of them.
Rainbow Dash blinked, then face hoofed. Of course Scootaloo knew how to count seconds, duh! Rainbow was being such a moron.
"I'm sorry, Scoots. It's just that when I saw you doing this wrong, I really wanted to help!"
Scootaloo looked confusedly at Dash as she chewed her S'more. "What am I doing wrong?" she asked.
"Making S'mores, I just wanna teach you how to do it right!" Dash pleaded.
"How am I making S'mores wrong?" Scootaloo frowned.
"You--" Dash furrowed her brow. "You're burning em', squirt," oh for Celestia's sake, did Scootaloo need glasses? New nostrils?? NEW TASTEBUDS!?--
--"Oh, I like em' burnt!" Scootaloo chirped, a cute smile on her face as she impaled another marshmallow on her stick.
Rainbow Dash was left eyes wide, and slack jawed as her train of thought came to a crashing stop. "HwWhah?" she blinked once, then twice, then she looked down at Scootaloo, who was happily burning a marshmallow. "Wat?"
Scootaloo rolled her eyes, still smiling. "Why does everypony always freakout when I tell em' that?"
"I dunno," Applebloom said as she trotted up to the fire, a panting Sweetiebelle in toll.
"Rarity screamed when I showed her how you make them," Sweetiebelle giggled.
"Ah think ya broke Rainbow Dash," Apple bloom said, giving the frozen blue pony a few gentle pokes.
"You--" Rainbow Dash gulped. "--You like burnt marshmallows?" it was absurd! It was preposterous! It was heathenism and treason, and a bunch of other big words Dash didn't know the meaning of!
The three fillies all burst out giggling, their cute little laughs bouncing around in Rainbow Dash's head like moths against a light bulb. After a moment, Dash returned to reality, her brain finally kicking it back into gear. She looked over to the CMC, who were happily roasting marshmallows and making S'mores.
Two of them were doing it the normal way, one of them--the little monster-- was doing it the weird way. The one that Rainbow Dash called her little sis. The one that... Dash swallowed, then she turned her weary eyes to her saddlebag, which was resting against the tent. Inside of it were the documents that, earlier, she had been so eager to show Scootaloo. The documents that already had her signature, and that had already been approved by the orphanage.
Oh, sweet Celestia, what had she done?
Author's Note
When I was a kid, I preferred my marshmallows burnt 
This story is just one massive joke, so don't worry about that dumb ending 
