The word is based on the verb to mope, which originally meant "to wander aimlessly"; it only later acquired the sense "to be bored and depressed".
The word mopery has been used by authors Thomas Pynchon (Gravity's Rainbow) and Dashiell Hammett (The Thin Man), among others, for whom it is usually a comic accent.
In Catch-22 (Joseph Heller, 1961), the mildly rebellious Cadet Clevinger is court-martialed by three angry officers, who accuse him of "breaking ranks while in formation, felonious assault, indiscriminate behavior, mopery, high treason, provoking, being a smart-guy, listening to classical music, and so on".
Similarly, in the 1984 comedy film, Revenge of the Nerds, mopery is defined as "exposing oneself to a blind person".
[2] According to Russell Baker, "mopery isn't a crime, but only an old policemen's joke in which it's defined as the act of displaying yourself in the nude to a blind person.