This story is a dark fanfic based off the creepypasta Abandoned by Disney, written by Robipony.
Some time after Tirek was defeated at the end of season 4, Pinkie Pie and Cheese Sandwich started working together to create a company called the Cheesy Pie Corporation. This company's goal was to entertain the ponies of Equestria and so they started creating theme parks.
Neon Lights learns about a theme park the company had made outside of Equestria in the Zebra nation and becomes curious about it after learning that it had been abandoned. Apparently the park had been abandoned due to a curse cast upon it by Zebra shamans.
After learning of Neon's plans Pinkie Pie sends him a letter attempting to persuade Neon to avoid going to the park. She even includes two tickets to a party at one of the theme parks so that Neon may take a friend to it. However instead of going to the party Neon sells the tickets and uses the money for a plane trip to the abandoned park.
At first Neon has difficulty finding it due to the Zebras being reluctant to help him. However Neon does manage to find the park and begins to explore and as he does Neon discovers a mascot room with a photo negative Pinkie costume laying on the ground and a Boneless costume with a pony skull still inside.
Neon explores further to discover an observation room where one of the night guards at left some reports regarding the event leading up to the closing of the park.
After reading the reports Neon attempts to leave but his path is blocked by the photo negative Pinkie mascot. After the monster tears off its own head Neon Lights manages to escape but not before being bit by the mascot's head.
The story ends with Neon Lights documenting the whole story on the plane back to Ponyville.
To read the story on FiMFiction follow this link:http://www.fimfiction.net/story/245946/abandoned-by-pinkie.