This story is a sequel to Eldritch Surprises

After Twilight found out Pinkie's secret, she decided the next best pony to tell was Applejack. After all, who best to keep her cool under intense stress and surprise than the most down-to-earth earth pony in town? She decides to just come out with it as bluntly as possible, Applejack appreciates bluntness right?

Pinkie is hiding a secret that has been tearing her apart. She decides to tell Twilight, but while working up the courage and best approach to tell her, the secret comes out violently anyway.
(Pre-Season 3 finale)