My Little Pony and... South Park?

"Oh my God you guys!" Cartman shouted as he galloped to the bus stop "You're not gonna believe it!"

"Ugh, what is it now, fatass?" Kyle said, knowing that whatever Cartman would say would be incredibly stupid.

"I have discovered a way... to make... PORTALS! To different universes, you guys!"

"Pfft, yeah right Cartman." Stan, Kenny and Kyle said in unison.

"I have, and I'll prove it to you guys! And everyone at school!"

MEANWHILE, IN EQUESTRIA...

Twilight Sparkle's friends gathered round as she tried out her new spell. Princess Celestia had sent her an extremely old book, which had some interesting spells in it. The one she was trying to perform could potentially create portals to different universes, which her friends were enthusiastic to see.

"You can do it, Twi!" Her friends encouraged her.

The minute the portal opened, everypony knew something bad was about to happen.

NOW, BACK TO SOUTH PARK...

Cartman had mixed some items together in a bucket; he was proving that he could open a portal to get $10 from Kyle.

Butters and Tweek were right at the front of the crowd (the crowd of Cartman's entire class). They knew it wouldn't work, but were trying to see what was in that bucket.

Cartman lit a match and threw it into the bucket of God knows what. A bright light erupted from that bucket to everyone's surprise, absorbing anyone unfortunate enough to be standing too close to it.

Back in Equestria...

As a bright light flashed from Twilight's horn, her friends watched in awe because they knew it was working.

All of a sudden though, the light flashed brighter than ever and the ponies (and Spike) realised the danger they were in. Then they were absorbed by the light.

Everyone was in a white void. Before Cartman could get his $10 off Kyle, they all fell unconscious. Before Twilight could begin to panic, they all fell unconscious.