Hadn’t seen this one before but I saw this in a book:

There once was a man from Peru,
Whose limericks stopped at line two

and then later in the same book they had

There once was a man from Verdun

There was a young man from south bend

Whose limericks all came to an end

Suddenly

Not a limerick but I want to share my favorite pun joke

I once submitted ten puns to a pun contest, hoping one would win, but
No pun intended

Reminds me of an oldie:

“Roses are red, Violets are blue. Some poems rhyme, This one don’t.”