Wiktionary
a. (context often sarcastic English) great or going well.
Wikipedia
Just Ducky is the 77th reel animated Tom and Jerry short, created in 1951 directed by William Hanna and Joseph Barbera and produced by Fred Quimby with music by Scott Bradley. The cartoon was animated by Irven Spence, Ed Barge, Ray Patterson, Kenneth Muse and Al Grandmain with backgrounds by Robert Gentle. It was released on September 5, 1953 by Metro-Goldwyn-Mayer and distributed by Metro-Goldwyn-Mayer.
Usage examples of "just ducky".
I reckon he should have cut up for something between seven and ten million dollars but the Board of Trustees only invested two million in the Matter-son Corporation and in non-voting stock, by God, which was just ducky for Bull Matterson.
Keeps your metabolism running pretty flat and steady, just ducky until the whole system crashes.
All the soldiers there could now vote, and the move would look just ducky to international observers.
It was just ducky being a half god if a god was your pop and your mom was human.