The limerick may be the only traditional form in English not borrowed from the poetry of another language. Although the oldest known examples are in French, the name is from Limerick, Ireland. John Ciardi suggests that the Irish Brigade, which served in France for most of the eighteenth century, might have taken the form to France or developed an English version of a French form. ... The contemporary limerick usually depends on a pun or some other turn of wit. It is also likely to be somewhat suggestive or downright dirty." [Miller Williams, "Patterns of Poetry," Baton Rouge: Louisiana State University, 1986]