Definitely not a song.....
There's a pdf file of the Wife of Bath at this link:
http://www.yorku.ca/inpar/Gay_Wife_1713.pdf
I can see that the play might appear funny to John thorpe, and he might well be thinking of it, but the quote (by Alison) is simply spoken text, not a song, or even a poem. Curiouser and curiouser.....