money from undisclosed or questionable sources.
currency of little value, as of a nation whose currency has been artificially inflated or recently devaluated.
any foreign currency.
Origin of funny money
First recorded in 1940–45
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
a sum of money so large as to be considered unreal
derogatory foreign currency
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Counterfeit money; also, money from an obscure or questionable source. For example, The police warned storekeepers that some funny money was being passed around town. This expression probably endures because of its rhyme. [1930s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.