Plato and a Platypus Walk Into a Bar is a delightful little book. It aims to explain the big topics in philosophy, and illustrate them with jokes. I learned a little and laughed a lot, so I'd say it succeeded.

Not all the jokes fit so well into the philosophic branch they're meant to illustrate, but this isn't meant to be a serious treatise. For example, here's a joke from the Philosophy of Language chapter:

A man goes into the confession booth and tells the priest, "Father, I'm seventy-five years old and last night I made love to two twenty-year-old girls—at the same time."

The priest says, "When did you last go to confession?"

The man says, "I've never been to confession, Father. I'm Jewish."

The priest says, "Then why are you telling me?"

The man says, "I'm telling everybody!"

I guess there's a point here about differing assumptions about the dialog, but it doesn't really matter: the joke is funny. The whole book is like that: you'll learn something about philosophy, and even if you don't, the jokes are funny.