A mock epic has the superficial trappings of an epic, but it tells the story of something that would be considered trivial in comparison to the topics of conventional epics. For example, "The Odyssey" focused on Odysseus' epic journey to Ithaca over the course of a decade, while the mock epic "The Rape of the Lock" focused on a noblewoman getting revenge for a bad haircut.
The mock epic is in verse form, just like a traditional epic. It starts with an invocation to the Muse, but it is meant to make fun of the various customs of the epic, rather than to honor them. Some tropes, such as legendary weapons or spiritual interventions, are also played for comedy. Where Beowulf might have used the sword Hrunting, the villain of "The Rape of the Lock" used a pair of scissors that the text referred to as a legendary blade, as though it were meant to be wielded against evil.
A mock epic is a form of satire. Authors who specialized in the form included Thomas Milton, Jonathan Swift and Alexander Pope. The main purpose of the mock epic to poke fun at the tendency of nobility to make trivial matters serious by writing about the people and events in intentionally flowery, overblown language that becomes humorous when simplified.