Well the story seems to be that pamphlet comes from a popular erotic 12th century Latin poem called Pamphilus, seu de Amore, which means "Pamphilus, or On Love."

But the poem itself seems to have been lost, and it doesn't appear to get a mention in Helen Waddell's Mediaeval Latin Lyrics or Wandering Scholars. So how popular and how erotic is a matter for surmise only.

I seem to remember there's a similar story to the one in Larry's song in Ancient Roman times. That doesn't imply it isn't likely enough to have happened as told in the 18th century as well.