After Chrysalis gets defeated and Shining Armor and Cadance return to the ground, Celestia tells Twilight that she has a real wedding to put together. But after a few misspells, twilights memories are altered, and after all she THINKS they did to her earlier makes this her chance to lose her temper and snap at them.
(note: this is a reimagining of the work of xd77, go check out his story before mine, right here)
(and before you ask, YES i have been given permission to do this story)
(update: im ABSOLUTLY DISGUSTING, and proud of it!)