Originally Posted By: Tromboniator
Wofa, I most respectfully challenge your rhythm analysis. Reduced to the simplest form, a limerick may be:

Bom ba da Bom ba da Bam
Bom ba da Bom ba da Bam
Bom ba da Bum
Bom ba da Bum
Bom ba da Bom ba da Bam

You can add one or two unstressed syllables before the first stressed syllable of any or all lines, you can add one unstressed syllable after all the Bams, you can add one unstressed syllable in both Bums.
(or even two sometimes)

To keep the original post short I didn't list all possibe exceptions. You're right in every particular.