I wonder now if that was some kind of "egads" modification.
Quite possible - some sayings came because someone misheard someone else using an older phrase...knew a guy who used the term “penny cash” because he thought that’s what someone said years before when saying “petty cash”. Done it myself a number of times - especially with the words to songs on old car AM radios....”Reach out in the darkness” became “Freak lout in the garden”...of course it may have been the pot of the time.....