Azeban Soksemo Among the Nereid

For months Alba had been telling everyone that a new dog had come to live with them. The family had grown used to her proclamations, and found it hard to argue the existence of another invisible dog, (especially since no one had been able to capture a photograph of it not existing), even if Alba said this one could run so fast as to fetch and return items before they'd even been thrown. Some friends (with cameras) still had their doubts, however.

One Sunday morning Alba got up early and walked out into the yard with nothing but an empty wash tub and some soapy water.
Neighbors heard her muttering, “I swear to Hatshepsut and a gaggle of Thutmose that I will scrub every bit of invisible off of this dog if it kills me….”
Later that afternoon several neighbors asked her when she had gotten a dog.