The Color of Magic by Terry Pratchett (1990, Paperback)

Pratchett borrows from Babylonian cosmology for his second, wacky flat-Earth yarn - set on an Earth.disk that rests on the backs of four elephants, who themselves stand on the shell of an enormous turtle. (And only Pratchett's characters would think of lowering themselves over the edge of the disk-in order to determine the sex of the turtle!) This time failed wizard Rincewind runs into problems when he encounters rich, bumbling circum - disk tourist Twoflower - whose luggage consists of a sapient pearwood box that trots around after him on hundreds of tiny legs. . . and snaps its lid at anyone it doesn't like. The innocent Twoflower sells some fire insurance to a shifty innkeeper, who proceeds to burn down his inn and the entire city of Ankh-Morpork. And what follows is madcap travelogue, involving: the disk's zany, often magical inhabitants; the Gods (atheists are liable to get their windows broken); a watery being who splashed down in the ocean, having fallen off a different Earth-disk; and Death with his scythe (whose timing is so poor that Rincewind keeps evading him). Not quite the gleefully insane parody Strata (1981) was, but frothy, inventive, and fun.