Brown Spots on the Ceiling

Alright, listen up, buttercup. This joke is playing on the fact that "Ho Fung Poo" sounds like "who flung poo." So, the joke is suggesting that someone with that name wrote a book about brown spots on the ceiling, implying that the spots are, well, you know... poo. And, let's be honest, you probably didn't know that 'poo' is a cutesy way of saying feces. Stay gold!