I think that the sibling just older than the new baby has the privilege of giving the baby their nickname.  Perhaps because they have the cutest way of saying things.  Or, maybe it is just their consolation prize for having lost their position as baby of the family.  When Drew was born, E.J. Called him Drewby, and the appelation has stuck until today.

Well, Mae has a shirt decorated with cupcakes.  The first time that she wore that shirt, Drew (who happens to be quite fond of said confection) spent the day pointing to each cupcake on her shirt and saying "cucake."  Since then, he has called her "baby cucake."  Ethan has joined in, and well, I just can help myself.