For months now, Betty and Coraline have had secret names for themselves. When playing, they often use them to refer to each other. Jonie (Betty) and Mayo (Coraline), have lots of adventures. We often ask Arthur what his pretend name is, and he says firmly that he's "Arthur!"
Sadly we know these names will eventually go by the wayside. Already Betty has stopped calling Arthur "Ayah," and she only rarely refers to Coraline as "Conga."