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From Unmariowiki

Tumble is an actually living person, who looks a lot like a Toad...just with a dice instead of Mushroom Cap, no visible arms and legs and is tiny, at 3'2 He was mentioned in Mario's Party of Parties 3 (6) and was also seen many times in the background of boards.

Tumble lives in ToadTown. he occasionally works at his part-time job at E. Gadd's Lab to save up for a Wii. he loves seeing Glitz Pit fights, and he loves eating 'Shroom Cakes while watching SMK.

He hosts parties for $30 a board.

In fact this character is even an user here!