I know quite a few limericks, but never competed. My dad (from whom I learned the one I posted) once told me about a classmate in medical school who could reel them off for hours.
There once was a man from Nantucket...
“The limerick’s furtive and mean;
You must keep her in close quarantine;
Or she slips to the slums,
Where she quickly becomes,
Disorderly, drunk, and obscene!”
I’m no patch on my dad, but I know a few.