Why was everyone fat and sassy
Why wouldn’t they be?!
To really answer your question, I have no clue! I tried to figure out if it was the name of a play or a revue or something like that, but as far as I can tell it was just an idiom that began sometime around 1890. There was a racehorse with that name in the 1910s but the two words began appearing together way before that! It seems to be used most often to refer to animals (“the horse looked starved but now he’s fat and sassy as ever”), farming (”Missouri crops appear fat and sassy this season”) and politicians (“the senator made a whistle-stop yesterday afternoon, looking fat and sassy”), if that means anything.
Fat and sassy
Fig. in good health and spirits.
Here’s the Google Ngram Viewer chart:
Looks like 1896, 1915, 1928, 1946, 1948, 1954 and 1989 are peak years for being fat and sassy!