The fabliau is a short, humorous and typically bawdy poem. They abounded as elements of poetry in France of the 12th and 13th centuries and first appeared in English some 100 years later. In French, the verse form is almost invariably in octosyllabic couplets, but is variable in English. The themes deal for the most part with domestic comedy full of sexual innuendo of the merchant and middle classes. Although some of the motifs are from oriental sources, many have a more immediate French source or analogue They have local settings and almost inevitably involve a lovers' triangle, trickery designed to gain favours from a desired woman most likely married or otherwise unavailable (one of the cloth or one too young etc.), and / or trickery designed to delude an ageing or otherwise undesirable husband to clear the way for a lover.
The earliest example in English is the anonymous Dame Sirith, composed ca. 1300. All other examples of fabliaux are Chaucerian Canterbury Tales: e.g. The Miller's Tale (considered the most outstanding example of a fabliau in Middle English), The Reeve's Tale, The Shipman's Tale, The Merchant's Tale, and The Summoner's Tale are also considered fabliaux, but with something added on. And, were he not to drunk to continue, The Cook's Tale was well on its way to becoming a fabliau as well.