Money easily gotten or earned: easy money for helping in the garden
The Dictionary of American Slang, Fourth Edition by Barbara Ann Kipfer, PhD. and Robert L. Chapman, Ph.D. Copyright (C) 2007 by HarperCollins Publishers. Cite This Source
Idioms and Phrases with easy money
Money obtained readily, with little effort and, often, illegally. For example, Winning the lottery—that's easy money! or I was wary of making easy money with the insider tips I'd been given.
[ c. 1900