Bit of a silly question, but I thought this was really funny and now I can't remember what it was in. A main character can read minds, including, I'm pretty sure, animals' minds, and is travelling with a cat, among others.
She (I think it was a she) tries to read the cat's mind, but the cat's thoughts just consist of "mip? mipmip?" in varying levels of impatience. Cats, apparently, don't know themselves what they want - that's your problem.
It sounds like it could well have been Terry Pratchett, but if so I don't know which book it was.