There was a young man from Peru
Whose limericks stopped at line two.
СЯУ ("Сегодня Я Узнала", аббревиатура заимствована у avva), что у этого лимерика есть вот такой извод:
There was an old maid from Verdun
The joke being that "Verdun" rhymes with one, so it can be inferred that if there was a second line, it would say "Whose limericks all stopped on line one."
(and even with an explanation that the narrator knows an unrecitable limerick about Emperor Nero)