Author: Pinkie Pie, shut up! No you can't name- You already did. Son of a...
Pinkie Pie: So author, you're always writing stories about me! How about I write a story about YOU!?
Author: That is a horrible... horrible... HORRIBLE ide-
Pinkie: Spectacularific! Let's do it!

A hack author (from "Extremely Terrible and Horrifying Stories" and "Mystery Pinkie Pie Theater 3000") is attempting to write his next magnum opus. Then Pinkie Pie happens.
Not the most original idea in existence, but hey, this is my take on how it would play out.