Dog dimension
From Tardis Wiki, the free Doctor Who reference
A "dog dimension" where "dogs were people and people were dogs" was a parallel universe theorised the exist by the Thirteenth Doctor.
Fearing for the fate of her universe if she were to be trapped in a such a dimension, the Doctor wrote a book containing a set of challenges and instructions intended to allow whoever found the book to temporarily take on the mantle of "the Doctor". (PROSE: Meet the Fam)
