I remember reading a comment a while back (I think on HN) about some running joke in one of his books about a cat (or maybe it was a dog?) and how _why had actu

I remember reading a comment a while back (I think on HN) about some running joke in one of his books about a cat (or maybe it was a dog?) and how _why had actually created this whole blog to keep the joke running outside of his book. It was hilarious and impressive, but I can't find it - anyone know what I'm referring to?