'You even match the interiors!'

I went through so many available puns. "Consider yourself part of the furniture!"
I refuse to believe being forgotten makes you stop existing as an imaginary friend. My own imaginary friends were creepy enough as it is.

And it occurred to me - If Riley's eleven, she's as old as this show and may have seen it as a toddler and associated Imaginary Friends with that gorgeous pink victorian interior design. 
Characters and setting (c) Pixar and Cartoon Network