“Where there’s smoke, there’s toast”

“Where there’s smoke, there’s fire” is an old proverb. A popular variant is “where there’s smoke, there’s toast”—meaning something was burnt. In the 1950s, this variant was used to humorously describe the cooking of new brides.
 
The saying “where there’s smoke, there’s toast” has been cited in print since 1933 and appeared in the Reader’s Digest in the 1940s.
 
A similar joke (cited in print since 1983) is “Dinner is ready when the smoke alarm goes off.” A Texas version of “where’s there’s smoke” is ‘Where there’s smoke, there’s brisket.”
 
   
The Free Dictionary
where there’s smoke, there’s fire
if it looks like something is wrong, something probably is wrong People like to think where there’s smoke, there’s fire, so they will always believe you were involved even if you weren’t.
 
Zazzle.com
Where there’s smoke there’s toast… aprons
 
2 August 1933, Greenville (PA) Record-Argus, “Modest Maidens” comic strip, pg. 7, col. 1:
Where there’s smoke there’s toast!
(A well-dressed woman is seen dashing to the smoke—ed.)
   
Google Books
Reader’s Digest
Volume 50
1947 (Google Books date might not be correct—ed.)
Pg. 110:
Where there’s smoke, there’s toast (Ruth H. Lane).
 
Google Books
Fun Fare;
A treasury of Reader’s Digest wit and humor

By Reader’s Digest Association.; et al.
Pleasantville, N.Y.
1949
Pg. 79:
Old saws sharpened: Where there’s smoke, there’s toast (Ruth H. Lane).
   
Google Books
September 1952, Boys’ Life, “Think and Grin,” pg. 74, col. 2:
Remember: Where there’s smoke there’s toast.—Henry MacLaren, Jr., Albany, N. Y.
 
Google Books
September 1956, Changing Times (The Kiplinger Magazine), pg. 2, col. 1:
Bride— A girl who has discovered that where there’s smoke there’s toast.
   
Google News Archive
31 December 1958, Sarasota (FL) Herald-Tribune, “In New York: It Happened Last Night” by Earl Wilson, pg. 10, col. 4:
Gretchen Wyler, who’s a bride, says, “Where there’s smoke, there’s toast.”
 
Google News
5 August 1970, Reading (PA) Eagle, “Quotations Old and New,” pg. 26, col. 2:
A groom is a fellow about to discover that where there’s smoke there’s toast. Lane Olinghouse.
 
Google News Archive
16 June 1987, Evening Times (Glasgow, Scotland), “Did You See?” by Eric Cook, pg. 19, col. 3:
DESPITE my surname I’m somewhat lacking in the culinary skills, tending to go by the old adage that where there’s smoke there’s toast.
 
Google Books
And I Quote:
The definitive collection of quotes, sayings, and jokes for the contemporary speechmaker

By Ashton Applewhite, Tripp Evans and Andrew Frothingham
New York, NY: St. Martin’s Press
1992
Pg. 341:
COOKING (Sayings)
Where there’s smoke, there’s toast.