Q: Can you please tell me the origin of the expression “my foot!”?
A: The word “foot” has traveled quite a bit since it showed up in Anglo-Saxon days as a noun for the part of a leg, below the ankle, that a person stands on.
It has meant a foot in measurement (since sometime before 1000), a foot of verse (around 1050), the foot of a bed (sometime before 1400), the bottom of a page (1669), a presser foot on a sewing machine (1877), and so on.
In the early 20th century, it showed up in “my foot!” (or “your foot!”), a colloquial expression of “contemptuous contradiction,” according to the Oxford English Dictionary.
The OED’s earliest example is from Mary the Third, a 1923 play by Rachel Crothers:
“Mother: She was honest enough to tell me that—and I could have persuaded—
“Father: Honest your foot! She’s fooled you—deceived you.”
And here’s a “my foot!” example from Hay Fever, a 1925 comedy by Noël Coward:
“Judith: It’s so silly to get cross at criticism—it indicates a small mind.
“David: Small mind my foot!”
Jonathon Green, writing in Green’s Dictionary of Slang, describes the phrase as a euphemistic variation on “my arse!”
The earliest example of the usage in Green’s Dictionary is from the April 1, 1905, issue of the Sporting Times. In the item cited, one man apparently corrects another for using “my hat!” instead of “my foot!”
“Said No. 2: ‘My hat! this is a really nice girl!’
“Said No. 1: ‘She is a nice girl, old chap, but that was
my foot!’ ”
(The phrase seems to be used here as a mild version of “my God!”)
The next example in Green’s (from The Harvester, a 1911 novel by Gene Stratton-Porter), clearly uses the phrase to suggest contemptuous rejection:
“ ‘She can’t leave her people. Her grandmother is sick.’
“ ‘Grandmother your foot!’ cried the old woman.”
In looking into your question, we came across a related exclamation that might interest you. Chaucer uses the oath “Christ’s foot!” in “The Miller’s Tale,” the second of the Canterbury Tales (circa 1386):
“Ey, Cristes fote! what wil ye do therwith?”