Ross May sent me this and I thought I'd answer it here…
Perhaps you, or one of your knowledgeable friends can help me answer a question. I'm a younger man and feel I have a good handle on most Looney Tunes jokes that reference pop culture from previous decades. Sometimes a character, especially Daffy, will exclaim "Aaaaaagony!" and feign anguish or even dying. It shows up enough I can tell it's a catch phrase or some reference, but I can't find out from where. I thought this would be up your alley of expertise.
Sadly, it is. At the studio where the cartoons were made, there was a gentleman named Smokey Garner who was a film editor and a projectionist. When he was given a difficult job to do, he would usually moan, "Aaaaagony, aaaaagony!" It became a catch phrase around the studio and it found its way into a number of cartoons. (So did his name. In What's Cookin', Doc?, Bugs calls to the off-camera projectionist and says, "Okay, Smokey! Roll 'em!")
Whether Mr. Garner got the phrase from somewhere else, no one knows. But that's where the gag men got it from.