Donna groans, "Oh I knew we weren't going to the zoo just to go to the zoo!"

She probably doesn't have to tell Andrew and Märet, but she will anyway, "He does this every time! With The Library, it was first 'we're going to the beach' and suddenly, nope The Library. And this time, 'Oooo let's go to the Zoo'. Will I ever learn?"

Yeah, Donna's ranting a bit.