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<font size=3>For "at the drop of a hat" (orig. <i>U.S.</i>
<i>colloq.</i>), the OED has:<br>
<b>1854</b> J. B. J</font><font size=2>ONES</font><font size=3> <i>Life
of Country Merchant</i> xv. 175 You said you'd marry me at the drop of a
hat!<br><br>
Google Books yields a few slightly earlier dates: 1837, 1842, 1844
(no view), 1850.<br><br>
For 1837, we have a quotation that not only is an antedating but also
gives a gloss! <br><br>
The Congressional Globe, Containing Sketches of the Debates and
Proceedings of the Twenty-Fifth Congress. Blair and Rives,
Editors. First Session---Volume 5. City of Washington,
1837. October 18, 1837, Volume 5, No. 9. Page 132:<br><br>
"They could agree in the twinkling of an eye---at the drop of a
hat---at the crook of a finger---to usurp the sovereign power; they can
not agree, in four months, to relinquish it."<br><br>
In the Senate, by Mr. Benton on "the bankrupt law", going on
for four or five pages. Thomas Hart Benton (1782-1858), nicknamed
"Old Bullion" and "an unflagging advocate for 'hard
money'" (Wikipedia). I don't know whether this is verbatim, or
a paraphrasing by a reporter.<br><br>
Google Books also gives a tantalizing but spurious earlier date of 1819,
with limited view: The Visionary (Religion) - Page 155:
"I started to think about all of it, since Michael has been here; he
practically cries at the drop of a hat, pitches fits, is constantly being
hard on you ..." However, the copyright page
can be found -- and it's 2010.<br><br>
Joel<br>
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