(French). A pun, a jest. From the “Jester of Kahlenberg,” whose name was Wigand von Theben; a character introduced in Tyll Eulenspiegel, a German tale. Eulenspiegel (a fool or jester) means Owl's looking-glass, and may probably have suggested the title of the periodical called the Owl, the witty but satirical “looking-glass” of the passing follies of the day. The jester of Calembourg visited Paris in the reign of Louis XV., and soon became noted for his blunders and puns.
Source: Dictionary of Phrase and Fable, E. Cobham Brewer, 1894
More on Calembour from Infoplease: