The standard form of a limerick is a stanza of five lines, with the first, second and fifth rhyming with one another and having three feet of three syllables each; and the shorter third and fourth lines also rhyming with each other, but having only two feet of three syllables. The defining "foot" of a limerick's meter is usually the anapaest, (ta-ta-TUM), but catalexis (missing a weak syllable at the beginning of a line) and extra-syllable rhyme (which adds an extra unstressed syllable) can make limericks appear amphibrachic (ta-TUM-ta).
The first line traditionally introduces a person and a place, with the place appearing at the end of the first line and establishing the rhyme scheme for the second and fifth lines. In early limericks, the last line was often essentially a repeat of the first line, although this is no longer customary.
Within the genre, ordinary speech stress is often distorted in the first line, and may be regarded as a feature of the form: "There was a young man from the coast;" "There once was a girl from Detroit…" Legman takes this as a convention whereby prosody is violated simultaneously with propriety.[6] Exploitation of geographical names, especially exotic ones, is also common, and has been seen as invoking memories of geography lessons in order to subvert the decorum taught in the schoolroom; Legman finds that the exchange of limericks is almost exclusive to comparatively well-educated males, women figuring in limericks almost exclusively as "villains or victims". The most prized limericks incorporate a kind of twist, which may be revealed in the final line or lie in the way the rhymes are often intentionally tortured, or both. Many limericks show some form of internal rhyme, alliteration or assonance, or some element of word play.
Verses in limerick form are sometimes combined with a refrain to form a limerick song, a traditional humorous drinking song often with obscene verses.
A notable Limerick - which won an Irish 'Listowel Writers Week' prize in 1998 - exemplifies the structure:
Writing a Limerick's absurd,
Line one and line five rhyme in word,
And just as you've reckoned
They rhyme with the second;
The fourth line must rhyme with the third.
Limerick (poetry) - Wikipedia, the free encyclopedia)
There once was this girl - an Asian
Who fancied it with a Caucasian
Her friends said be bold
At least two thousand all told
She soon found her true vocation