Limericks are like haiku, a short pithy form, but unlike haiku, the rhythm is more flexible. You don’t have to begin on the downstroke, the first beat of the bar, so to speak. The second word in this limerick is the first stress.
Also, as it’s a common, low culture form, there are no rules that can’t be broken so long as you stick to meter and rhyme, more or less. It’s traditional to end with a punchline, but the subject doesn’t have to be comic. This one opens in the middle of a musical narrative.
So Johnny said “Bonnie, it’s true
I would, but my digeridoo
My banjo and bass
Won’t fit into the case
With Donny’s trombone in there, too”


