How come the expression how come came to be used as an interrogative? This Americanism arose in the mid-1800s, and is still widely used in informal contexts. This is part of a complete episode.
whimperative n. a command or request phrased as a polite or indirect question. Also wh- imperative. Editorial Note: This word is especially used in the linguistic study of discourse. Thanks to Ben Zimmer for helping to clarify this definition...