One day, in Equestria, Twilight Sparkle and her friends were doing their everyday stuff, Rainbow Dash was clearing the sky of clouds, Rarity was making dresses, Applejack was bucking apples off of trees, Flutter Shy was taking care of her critter friends, Pinkie Pie was making everypony smile by just being Pinkie Pie, and Twilight Sparkle was reading another “Star-swirl the bearded: Alternating spells volume VI”. While she was reading, she came across a size changing spell.

“Hmm, this is an interesting spell; it seems a bit difficult though… I should try a growth spell first.” Said Twilight, So Twilight decided to get an apple and make it grow. She looked at the book and then the apple, then she said “Okay, I can do this!” Then she closed her eyes and focused her energy into her horn and it began to glow. Just as this happened, the apple began to grow in size until it was as big as her. “Wow! It worked!” She said in excitement. “Alright, now let’s see I can make it shrink back to its regular size.” She stated. While she was practicing, Pinkie Pie just happened to trot by and saw Twilight shrink the apple back to its original size.
“Ooh, I wonder what it would be like to be small; I would be a pipsqueak, but it would be so fun!” She said.

Now Twilight was about to change the apples shape when she heard Pinkie Pie knock. Bang, bang, bang “I’m coming!” Shouted Twilight, She opened the door and saw nopony, but then Pinkie hung from the top of the door and shouted
“SURPRISE!” Twilight was slightly startled by this and shot an apple to orange spell at a banana, and the banana was turned into an orange, partly.
“Pinkie Pie, don’t do that to me!” Shouted Twilight,
“Sorry,” Pinkie said, “but I can’t help but take a surprise opportunity when I see one!” Twilight sighed and said,
“What do you want Pinkie Pie, I am practicing some magic on an apple, so make it quick.” Pinkie quickly replied
“I want you to practice your shrinking magic on me! Please.”
“No!” Twilight said
“Pretty please with a cherry on top!” Pinkie begged. They fought until 11:00 PM, then Twilight finally yelled “Ugh, FINE!”

“Are you sure about this Pinkie Pie? I don’t want you to get hurt.” Said Twilight concerned.
“Oh please, this’ll be easy as pie!” Pinkie joked.
“Okay!” said Twilight. Then Twilight made her horn glow with a purple aura and shrunk Pinkie Pie to the size of a fly,
“Yay! I’m a Pink-squeak” She said.
“I am glad you liked it Pinkie Pie!”
Pinkie then interrupted “Ooh, can you eat me?!”
Twilight then yelled in a worried tone “WHAT!?” Pinkie said
“Eat me, I promise I’ll taste just like cookies and cupcakes! Plus I’ve always wondered what it would be like in somepony’s belly! Please!”
Then Twilight said, “Okay, but try not to get hurt.”

With that, Twilight opened her mouth and Pinkie climbed inside,
“What do I taste like?” She asked,
“Like cookies and cupcakes!” said Twilight.
Pinkie then said “And now for the fun part!”
Twilight quickly said “Wait what?” Just then, Pinkie Pie went to the back of Twilight’s throat. Twilight had no choice but to swallow. Then Pinkie Pie went down Twilight’s Esophagus and fell into her stomach,
“Don’t ever do that again!” Shouted Twilight,
“Oh my, gosh, pinkie, are you alright?” Twilight then shouted in worry,
“I am just super-duper Perfect!” Pinkie said with great enthusiasm.
“This is the best bed EVER!”
Then Twilight said “Okay Pinkie, sleep tight, IS IT SERIOUSLY MIDNIGHT!” And with that, Twilight went to bed with her friend Pinkie Pie inside her stomach, and slept worriedly through the night.

Author's Notes:

Pinkie Pie visits Twilight in her library (I Wrote this before season 4 ended) while she is practicing size magic, doesn't end well.