Füt Stüff Book is a book seen in the episode "Fionna and Cake and Fionna". It is seen while Ice King is talking to the Other Fionna. It is located where the Butt Stuff Book was located in "Blank-Eyed Girl".
Only the binding of the book is seen in the episode. It is yellow with brown lines and two brown circles. The words "Füt Stüff" is written in a 3d dark brown font, and there is a brown diamond near the bottom.