My Little Pony and... South Park?

"Look girls, I think we could get home if we went to the local school..." Twilight suggested, hoping they could find the portal she went through before to get to the human world.

"Ugh, we have to go to SCHOOL?" Rainbow Dash groaned, for she thought that school was way too boring.

"Rainbow! It may be the only way we can get back home!" Twilight replied. Unfortunately for them, it was not. Even worse for them was that Mr.Mackay saw them outside the school and forced them to go in, giving them a late detention (because it was the middle of the school day!) They were sent straight to Mr.Garrison's class (Other than Spike, who was sent to the kindergarten class.)

The boys had told Celestia their story, and she had been sitting there for a couple of minutes thinking what she could do.

"Kyle, was there a book on the table in the library?" Celestia asked, hoping the book would contain the spell to send them back.

"Um, yes but it was all burnt up..." Kyle replied sounding slightly confused. Celestia frowned, because the book was actually Starswirl the bearded's one of a kind extremely advanced spell books. In fact, it was the last book he wrote before his mysterious disappearance... But that's not important. What's important is what happens next!

"Unfortunately the spell was only in that book, however there could be another way for you to go back where you belong... There's a book in the-" Before she could finish her sentence, the earth shook beneath them and a green spike of magic pierced Celestia through her pale neck.

"Oh my God, you killed Celestia!" Kyle yelled.

"You basta- wait, what the hell is that?!"

Queen Chrysalis flew over to Celestia's lifeless body and cackled as her changeling army swarmed across Canterlot.

"This... is... BORING!" Rainbow Dash shouted. She and her friends had been in detention for two hours, but still had five more to go.

"There will be no talking in detention, M'kay?" Mr.Mackay scolded them. Rainbow Dash grumbled and rested her head on the table. Pinkie Pie had been asleep most of that time, because her coffee high had disappeared along with all of that energy. All of a sudden a strange noise came from the distance.

"Huh, wha was that?" Pinkie Pie mumbled as she woke up.

"It sounded like a... n-no, it can't be..." Fluttershy answered.

"What is it Fluttershy?" Rarity asked.

"It sounded like, and this will sound crazy-"

"Just spit it out!" Applejack said.

"A guinea pig..." As she said that, the noise came again only much louder.

"G-g-GUINEA PIGS?" Spike said, sounding terrified.

"Oh... my... God, M'kay..."