What's So Funny, Ketu? Book

Traditional literature, African folk tale of the Nuer people.
Ketu is blessed by a snake with the dubious gift of being able to hear what animals say. Once he starts to hear them, he laughs so hard it disrupts his family life (baby wakes up, wife gets irritated....) I loved the line drawn illustrations by Marc Brown and the design of this book, but the story didn't add up to much for me. Usually a tale like this has a clear lesson - what am I missing?