A female at her computer repeatedly refreshes a package shipping status (presumably FedEx or UPS) page in hopes that a desired item has proceeded further in its journey from distributor to her doorstep. The caption describes how, in our modern information-rich realtime-updated era, we may have unrealistic expectations about how long traditional physical processes may actually take. The Author proposes that this will be humorous because it will resonate with the cognitive dissonance that many geeks experience translating between the physical and electronic worlds.
It is also a nod at the irrational behavior of many geeks who obsess over new or desired possessions. It is obviously irrational to expect that between two quick checks the location of the package will suddenly change, but she feels driven to check because of her fixation on the object (presumably a math text, a new annotated copy of the Kamasutra, or a computer hardware component) is so strong that it overrides an obvious conclusion. This fixation is often short-lived among the self-proclaimed geeks, but often can be surprisingly strong for someone not diagnosed with a mental illness or cognitive disorder.
CURATOR’S NOTE: In a rare change of character, this XKCD features a female engaging in irrational, fixative behavior. Usually females are portrayed with more balanced and socially-normalized perspectives and actions.