Up and down the City Road
In and out of the Eagle,
That's the way the money goes,
Pop goes the weasel!

Half a pound of tuppenny rice,
Half a pound of treacle,
Mix it up and make it nice,
Pop goes the weasel!

Every night when I go out
The monkey's on the table;
Take a stick and knock it off,
Pop goes the weasel!

from Denslow's Mother Goose: Being the Old Familiar Rhymes and Jingles of Mother Goose Edited and Illustrated by W.W.Denslow, New York: McClure, Phillips & Company, 1901

"The popular explanation of this music-hall-song-cum-nursery-rhyme is that the weasel is an implement used in the cobbler's trade. To pop was to pawn the weasel on a Friday night...in order to get the money to go Up and down the City Road and enjoy one's self at such public houses as the Eagle.

This excerpt from:
The Annotated Mother Goose, Nursery Rhymes Old and New,
arranged and explained by William S.Baring-Gould & Ceil Baring-Gould

Tony