"A fabliau is a brief comic tale in verse, usually scurrilous and often scatological or obscene. The style is simple, vigorous, and straightforward; the time is the present, and the settings real, familiar places; the characters are ordinary sorts -- tradesmen, peasants, priests, students, restless wives; the plots are realistically motivated tricks and ruses. The fabliaux thus present a lively image of everyday life among the middle and lower classes. Yet that representation only seems real; life did not run that high in actual fourteenth-century towns and villages -- it never does -- and the plots, convincing though they seem, frequently involve incredible degrees of gullibility in the victims and of ingenuity and sexual appetite in the trickster-heroes and -heroines.
(The Riverside Chaucer, p. 7.)
The fabliaux was, until Chaucer's time, a genre of French literature, in which it flourished in the thirteenth century. One of the minor problems about Chaucer's fabliaux is why he turned to a genre that had, in effect, been dead for a hundred years. Comic tales were very popular in Chaucer's time, but the more sophisticated were almost always in prose (as in the case of Boccaccio's Decameron). Chaucer had no models in English, and despite the vivid contemporary tone of Chaucer's fabliaux, they are in some ways his most Gallic works.
Perhaps Chaucer was attracted to this genre by its most striking characteristic, its irreverence. This is a common feature of all forms of comedy, but it is a major and almost invariable