Flipside is a fictional location in the Wii video game Super Paper Mario. The town the main area in the game, much like Rogueport was for Paper Mario: The Thousand-Year Door. After encountering Count Bleck in the beginning of the game, Mario is awakened and transported to Flipside by the timid Pixl Tippi. She takes him to the house of Merlon, a wizard living in the area. From the top of a tower there, Mario and his partners can access other worlds, and in the background above the tower is a growing Void put into place by Bleck that will gradually consume the town.
As Mario gains more partners, he is able to access more areas of the city and eventually find a mirror image of the town called Flopside where they meet another wizard named Nolrem (Merlon spelled backward). The two wizards are friends and the only two people who know this secret. The residents of Flipside are generally good-natured and friendly, but the residents of Flopside are exact polar opposites of their Flipside counterparts.
After the fight with Super Dimentio, Nastasia, O'Chunks, and Mimi are seen walking around town and the player can talk to them (Nastasia in Flopside's 3rd floor, O'Chunks in Flipside's 3rd floor, and Mimi in World 2-2, Merlee's mansion).