Pinkie Pie had always thought she was the best party pony, but when Cheese Sandwich shows up at Ponyville, all the ponies and especially her best friends were happy about his presence, and while Pinkie Pie wasn't quite thrilling. She doesn't leave the house, intent on avoiding Cheese Sandwich and the others. But when Pinkie Pie's friends realize that Pinkie Pie has stopped showing up, they get worried and decide to go to Sugarcube Corner. But when they see that Pinkie Pie has a smooth mane and dark pink fur, their friends are worried.