She is the coolest pony ever. Edward fears that she shall make him into cupcakes.
Years ago, Pinkie Pie had an affair with Rarity which produced the revolting bastard child known as Alice Cullen. She inherited Pinkie's energy level and Rarity's love of fashion, and combined them in the worst way imaginable. Pinkie was greatly embarrassed and vowed to kill Edward to compensate.
Remember... PINKIE PIE IS BEST PONY!