A round-the-world trip, as you know, is a journey around the globe. The easiest way is around a light bulb. What, you say, around the Earth itself? Well, if there’s something you can use—like a plane, wild geese, or the Space Ship—then please. Only getting lost isn’t hard either: on cities and countries the names aren’t written. And it’s all because of people. Some people even assume these huge creatures are intelligent (after all, rats are sometimes pretty sharp), but they clearly don’t shine with intellect. Once they see the Space Ship, they gather in a crowd and start muttering something.
By the way, planets also somehow aren’t labeled. But with planets it’s easier: to figure them out, the nommes have very smart machines that remember the way home.
No matter what Terry Pratchett writes, he always makes the reader laugh until the tears come—or, in a sad way, smile and sympathize with the unfortunate heroes.