Where does the term Smackeroonies come from?

The meaning of "smackers" or "smackeroonies" is a little more phonetic than most, with the term originating from the sound a note makes when literally being 'smacked' into the palm of your hand.

What is Monkey financial term?

A "monkey on the house" or simply a "monkey" was a mortgage. At that time 500 pounds was a huge sum of money to the poor people who predominantly used such slang and the only way to raise that amount of money would have been to mortgage the house.