Keith (Infinity Apartment)
From Jenny Everywhere Wiki
Keith was a normal human man from one of the universes where the Infinity Apartment existed. He was a neighbour of Jenny Everywhere, and refused to believe her about the Apartment's multi-dimensional nature until, after inviting him over, she opened the door again only for it to now exit to Jenny's front door in a universe populated by Dragons instead of Keith's own homeworld. (COMIC: Infinity Apartment)