What is Doodly-squat?
1.
Of no significance, rank or importance. The word “doodle” was in wide slang usage throughout the 19th Century to mean a fool, a clueless soldier or a penis. The term was in wide use during the Great Depression and was joined by the updated version "diddly-shit" in the 1960s.
“My gal is red hot (Your gal ain't doodly-squat)”
-- from the oft-covered 1950s song "Red Hot"
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