shingle-eating grin, crap-eatin' grin, canary-eatin' grin, sugar-eating grin, crud-eating grin

[Garson O'Toole]

The OED has the phrase "shit eating grin" with two different senses.
The earliest cite is in 1956.
1956 J. Moffett in New World Writing No. 10. 16 You've got the most
shit-eating grin I ever saw.

For entertainment and perhaps edification I looked for evidence before
1956 by allowing matches for milder expletives, euphemisms, and other
words. The matches are in GB and are mostly unverified.

In 1949 (not verified) the phrase "shingle-eating grin" is used.
Perhaps the speaker thought the "shingle" would be more appetizing
than the "shit" when considering "shit on a shingle". Or maybe it is
unrelated.

1949, The American Legion magazine, Volumes 46-47, American Legion
(Not verified on paper; Probe with 1949 looks ok; GB Volume number matches year)
http://books.google.com/books?id=N7jvAAAAMAAJ&q=shingle#search_anchor
<Begin excerpt>
... a butch haircut, a shy, shingle-eating grin, and a firm conviction
that no real bullets will be used. The Kid wanders about telling the
others how different Army life is from life on the farm in Kansas. ...
<End excerpt>

In 1950 (not verified) the phrase "crap-eatin' grin" was published. So
this instance might be useful as a bracketed citation.

1950, The Brother by Feike Feikema, Frederick Feikema Manfred
(Not verified on paper; Worldcat and library catalog entries agree
with year of publication)
<Begin excerpt>
The two heads looked into the shack again. Thurs asked, "This nest
yours?" "By God, it talks," the shorter gray-whiskered bum said. "And
it's givin' with the crap-eatin' grin," the taller brown-whiskered bum
said.
<End excerpt>

In 1954 (not verified) the fine phrase "canary-eatin' grin" was printed.

1954, A Thousand for the Cariboo by Bill Gulick
(Not verified on paper; Worldcat and library catalog entries agree
with year of publication)
http://books.google.com/books?id=4W03AQAAIAAJ&q=canary#search_anchor
<Begin excerpt>
"Damn it, Wynn, get that canary-eatin' grin off your face and talk
plain!" "Well," Wynn said, turning the glass round and round between
his hands, "it could be Gould would be lucky enough to drive them
steers across country he's never ...
<End excerpt>

In 1954 (not verified) "sugar-eating grin" is used in a military
magazine. Sugar is a common euphemism for shit.

1954, The Leatherneck: Volume 37
(Date probe for 1954 looks ok; Volume 37 was 1954 according to a scan
of December 1954 issue; Issue with quote is unknown)
http://books.google.com/books?id=wazvAAAAMAAJ&q=%22sugar-eating%22#search_anchor
<Begin excerpt>
After a jumper hits the deck and deflates his chute, he can uncork an
emotional reaction. Usually, it's a sugar-eating grin. The smiles were
broader following the second jump. On the third day, the operation hit
a snag.
<End excerpt>

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