I've very infrequently heard the expressions:
"Don't say 'boo' [to them]"
(meaning don't say anything, no matter how small or insignificant)
or
"I didn't hear 'boo'"
(meaning I didn't get any kind of reply or acknowledgement, no matter how small or insignificant.)
I've looked online for the etymology of the phrase, but have come up empty. I did find a small sample of pages where the phrase is used. See:
http://www.gofigure.co.nz/doc/content/view/896/21/
https://idioms.thefreedictionary.com/say+boo
https://idioms.thefreedictionary.com/didn%27t+say+boo
https://forum.wordreference.com/threads/she-hasnt-said-boo.1223325/
Would anyone know the origin of this phrase? Google Ngram shows "hear boo" appearing around 1910, then a resurgence in the late 1960s:
I'm aware that "boo" is a word used as an exclamation to scare someone. But that seems opposite of the way "boo" is used in these expressions. Maybe it's used because it's just a short word…but why that particular short word?
Best Answer
Saying bo [or boo] to a goose
Eric Partridge, A Dictionary of Slang and Unconventional English, second edition (1937) has this entry relevant to expressions involving "saying boo":
Various searches at Early English Books Online related to "saying bo [or boo] to a goose" turn up a number of matches from as early as William Watson, A Decacordon of Ten Quodlibeticall Questions Concerning Religion and State (1602); unfortunately, I have not been able to find the relevant goose-bo[o]ing excerpt from that treatise in a snippet-view search of the text at Google Books. Still, a number of relevant matches do turn up, starting with two from 1606.
From Barnabe Rich, Faultes Faults, and Nothing Else but Faultes (1606):
From Thomas Dekker, The Seuen Deadly Sinnes of London Drawne in Seuen Seuerall Coaches ... (1606):
From Thomas Middleton, A Chast Mayd in Cheape-Side (ca. 1613):
From I.H., The House of Correction: or, Certayne Satyricall Epigrams (1619):
From John Taylor, A Iuniper Lecture With the Description of All Sorts of Women, Good, and Bad (1639):
Taylor's example is noteworthy for being the earliest instance I could find in which the thing said was "boo" rather than "bo."
And from Thomas White, "Mr. Blacklow's Reply to Dr. Layburn's Pamphlet Against Him" (1660):
Saying bo to a goose follows from a more general circumstance of saying bo. A search for the more generalized expression turns up instances from as early as 1526. From Walter Smith, XII. Mery Iests, of the Wyddow Edyth (1526/1573):
Saying boo without a goose in sight
Examples of "saying boo" in the sense of "saying something [or anything]" without an accompanying goose are fairly common in U.S. newspapers from 1836 onward. Here are some early examples.
From "A Change of Mind," in the Crawfordsville [Indiana] Record (February 20, 1836), reprinted from the Cincinnati [Ohio] Mirror:
From a letter to the editor of the Constantine [Michigan] Republican (August 16, 1837):
From "Nettle Bottom Ball," in the Ottawa [Illinois] Free Trader (May 30, 1845), reprinted from the St. Louis [Missouri] Reveille:
From "Jedediah Parsley's New-Year's Parin' Bee," in the Richmond [Indiana] Palladium (March 17, 1846):
From "How Paddy Casey Got in the Calaboose," in the [Hawaii] Polynesian (July 8, 1848), reprinted from the New Orleans [Louisiana] Mercury:
From "Only Half Married," in the Pontiac [Michigan] Gazette (February 7, 1852):
From "Mollie Pickwood," in the Pontiac [Michigan] Gazette (April 1, 1854):
The fuller "boo to a goose" was not lost at this period, however, as we see in this example from "A Little of Every Thing," in the Boston [Massachusetts] Pilot (February 21, 1846), reprinted from the Advertiser:
Conclusions
Expressions of the form "say boo" (or "say bo") go back almost 500 years. The most popular early form of the expression seems to have been a taunt along the lines of "wouldn't say bo[o] to a goose." The expression (usually without the goose) continues to be common in the United States, where it continues to mean much the same thing that it did in the early 1600s. Perhaps the most surprising thing about "saying boo" is that, despite its long record in English, it remains colloquial or at least informal.