Related to fiddle-de-dee: fiddling around
Used to express mild annoyance or impatience.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
rare an exclamation of impatience, disbelief, or disagreement
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
or fid•dle•de•dee(ˌfɪd l dɪˈdi)
(used to express irritation, dismissive indifference, or scorn.)
[1775–85; fiddle + nonsense syllables]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.