Crapaud is sometimes used as an incorrect reference to the Fleur-de-lys on the ancient heraldic flag of the kings of France. The three fleurs-de-lys were sometimes misinterpreted as "three toads erect, saltant", instead of "three lily flowers".
Jean Crapaud, also Johnny Crappeau or Johnny Crappo, defined by Webster's Online Dictionary, "is a jocose name given to a Frenchman. It is intended as a national personification of the French people as a whole in much the same sense as John Bull is to the English. It is sometimes used as a literary device to refer to a typical Frenchman, usually in the form of Monsieur Jean Crapaud." The usage of the word "crapaud" in this case is similar to the derogative use of the word "frog," referencing the supposed French affinity for frog legs as a delicacy, and thus considered to be a slur and derogative.
^Ebenezer Cobham Brewer (2001). The Wordsworth Dictionary of Phrase and Fable. pp. 438–439. ISBN1840223103. Fleur-de-lis, -lys, or -luce (Fr. lily-flower). The name of several varieties of iris, and also of the heractic lily, which is here shown and which was borne as a charge on the old French royal coat-of-arms. In the reign of Louis VII (1137-80) the national standard was thickly charged with flowers. In 1365 the number was reduced by Charles VI to three (the mystical church number). Guillim, in his Display of Heraldrie, 1611, says the device is "Three toads erect, saltant".