A munchkin is an immature player, to whom is ascribed every vice of the egoistic, unsophisticated gamer. The term comes to us from The Wizard of Oz, in which a munchkin is a short person from a faraway land. The older generation of wargamers applied the term to younger, perhaps very young, players who invaded the wargaming hobby with their improvisational, powergaming attitudes, Monty Haul style campaigns, and fascination with their own characters. In short, the original munchkins eventually came to dominate the RPG world with their interest in theatrics, heroic PCs, fun-oriented play style and interest in elaborate backstories. The term carried forward a generation, and is still used to label those whose gaming style is deemed, on whatever basis, to be immature and inferior.
Ironically, many younger players, joining the game through Dungeons & Dragons and other tactically oriented games, are earning the label of munchkin from older, more sophisticated gamers who like to play storytelling games in which they are immortal, inconceivably powerful, and stylishly evil characters such as vampires, wielding katanas, riding bikes, and possibly thrashing on guitars.