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 once was a bard from Japan
Whose limericks never would scan
When told this was so
He replied, 'Yes, I know"
“But I always try and fit as many words into the last line as I possibly can.”

there’s really no need to say more

The audience always wants more

There was a young man from south bend

Whose limericks all came to an end

Suddenly