Ernesto, keep your voice down for you’re in the library! (Oops… sorry, librarian.)
The fact that he gave Petey a cheese cracker (as evidenced by the librarian telling him “no food”) should mean he is not imaginary.
Carry that imaginary cracker to the librarian. Ask the librarian about it.
Isn’t this the first time Petey has expressed some doubt about Ernesto’s existence?
No, but his million friends are.
I have some friends that I wish were imaginary!
Petey, you are right! Disregard that loud disembodied voice in panel 3!