Humor in math books:

3.2. Definition. Let X be a topological space, then X is said to be compact provided each open cover of X contains a finite cover. (Here "open" refers to a property of the D_a, while "finite" refers to a property of the indexing set A.)

The following picture of the notion may help. Suppose a large crowd of people (possibly infinite) is standing out in the rain, and suppose each of these people puts up his umbrella, then they will all stay dry. It is, of course, possible that they are all crowded so compactly together that not all, but merely a finite number of them need put up their umbrellas, and still they will all stay dry. We could then think of them as forming some sort of compact space. It is, of course, assumed in all this that the umbrellas are open.

—John D. Baum, Elements of Point Set Topology