What should we read?

yesterday afternoon I was looking through a bunch of old letters, and mostly just sorting them...Ben asked me to read one to him at one point, but I wanted to keep sorting so I told him, "not right now..."
When I put him on his bed, I asked him...
Me: Do you want to read a letter?
Ben: I want to read a book.
Me: You want to read what book?
Ben (very mechanically): Mike Mulligan and the steam shovel.
Well...of course he wants to... he always does!
Me: Well, you want to read Katy?
(Hoping to read something else...)
Ben (thinking I'd said "you want to be Katy?"): Yes, I be Katy and you be JoJo.
Our dear nieghbor, Mrs. Webb is moving to be with her daughter, so her daughter has come up here twice recently. Ben really likes her dogs, and their names are Katy and JoJo.