I just obtained a book called The Penguin Book of Limericks, compiled & edited by E. O. Parrott, a very catholic collection running the gamut from intellectual wit to X-rated humor. My favorite, so far, is the following limerick by "Anon."
'I must leave here,' said Lady De Vere,
'For these damp airs don't suit me, I fear.'
Said her friend: 'Goodness me!
If they don't agree
With your system, why eat pears, my dear?'
UPDATE: Here is another one that gave me a stitch in my side for laughing. The author, again, is "Anon." That guy sure is funny!
Said Queen Isabella of Spain,
'I like it now and again;
But I wish to explain:
That by "now and again"
I mean now, and AGAIN and AGAIN.'