The concept of an imaginary friend of this nature is referenced once, though not discussed. A short comic in Cartoon Network Block Party #31 shows a kid who imagined a nicer, hotter version of Frankie being forced to give her up for adoption because she upsets his parents. I don't know why they wrote this, because it would seem to suggest that it is in fact possible (if only for certain precocious adolescents) to imagine a living, breathing sex doll into reality. This seems like the sort of thing that a writer's room would want to avoid.
Edit: Despite appearing in order when I try to edit, the thumbnails of the comic below seem to be out of order. I don't think I can change this; you guys should be able to figure it out.