Double dactyls

A dactyl is a three-syllable grouping with the accent on the first syllable. A double dactyl poem has 8 lines. Lines 4 and 8 are a dactyl followed by a single stressed syllable. The other lines are double dactyls (6 syllables, with stress on the first and fourth). There is a single rhyme: lines 4 and 8. All the above must be strictly adhered to. In particular, extra unstressed syllables are frowned upon. Additional traditional requirements: Line 1 is supposed to be a nonsense word like "Higgledy-Piggledy"; line 2, should include the protagonist's name (there is some variation allowed); one of lines 5, 6 or 7 is supposed to be comprised of a single word (some say this is an absloute, others are more lenient).

A limerick has 5 lines, with three stresses in lines 1,2,5 and two stresses in lines 3 and 4. The rhyme scheme matches the meter: Lines 1, 2 and 5 all rhyme, and lines 3 and 4 rhyme with each other. The meter is dactyl-like in that there are usually two unstressed syllables after each stressed syllable. The limerick allows flexibility in the number of unstressed syllables that might come at the beginning of a line (usually 1, but it can vary) or whether there are unstressed syllables at the end of the lines (if so, probably there are the same number in lines 1,2,5 due to rhyming and the same for lines 3 and 4). Limericks are traditionally bawdy, but for these purposes one might substitute "mathy" (or go ahead and be bawdy if you dare).