“Loose lips sink ships” is a World War II saying meaning that one shouldn’t talk too much (“loose lips”), or the enemy might overhear the conversation and use the information to attack (“sink ships”). A poster, “Loose Lips Might Sink Ships,” was created Seagram Distillers Corporation by the designer Seymour R. Goff (also known by the pseudonym “Ess-ar-gee” or Essargee) and has been cited in print since at least February 4, 1942. “Loose lips sink ships” (without the word “might”) has been cited in print since at least March 11, 1942.
 
The WWII saying is still known and sometimes used in the military, in intelligence circles, in politics, in business, and elsewhere.
 
 
Wikipedia: Loose lips sink ships
Loose lips sink ships is an American English idiom meaning “beware of unguarded talk”.
 
The phrase originated on propaganda posters during World War II. The phrase was created by the War Advertising Council and used on posters by the United States Office of War Information.
 
The most famous poster that helped popularize the phrase was created for the Seagram Distillers Corporation by the designer Seymour R. Goff (also known by the pseudonym “Ess-ar-gee” or Essargee). This type of poster was part of a general campaign of American propaganda during World War II to advise servicemen and other citizens to avoid careless talk concerning secure information that might be of use to the enemy. The British equivalent used variations on the phrase “Keep mum,” while in neutral Sweden the State Information Board promoted the wordplay “en svensk tiger.”
 
OCLC WorldCat record
Loose lips might sink ships
Author: Essargee.; Distillers Corporation-Seagrams Ltd.
Publisher: New York City, N.Y. : Seagram-Distillers Corp., [between 1940 and 1945]
Edition/Format:   Image : Picture : English
 
4 February 1942, Omaha (NE) Evening World-Herald, pg. 10, col. 2 photo caption:
(The poster “Loose lips might sink ships” is shown—ed.)
“Loose lips might sink ships” warns poster, and mum’s the word these days at draft board No. 4 in South Omaha.
 
8 February 1942, San Francisco (CA) Chronicle,  “Somewhere High in the Fog Aircraft Spotters Keep a Vigil,” pg. 14, col. 5:
One wall of the plyboard penthouse was plastered with signs.
 
“Keep your shirt on, your chin up, and your mouth shut!” read one stern warning. Another was: “Loose lips might sink ships.”
 
11 March 1942, Port Arthur (TX) News, “Lagniappe,” pg. 6, col. 5:
Port Arthur in general and seamen here in particular will give 100 per cent endorsement to a poetic two-line warning appearing in the current issue of the “Pilot” National Maritime union newspaper.
 
It reads:
 
“Loose Lips
Sink Ships!”
 
OCLC WorldCat record
Do loose lips sink ships?: The meaning, antecedents and consequences of rumour and gossip in organisations
Author: Grant Michelson; V Suchitra Mouly
Publisher: Emerald Group Publishing Limited
Edition/Format:   Article : English
Publication: Corporate Communications: An International Journal, 9, no. 3 (2004): 189-201
Database: ArticleFirst
 
OCLC WorldCat record
Code of silence. Loose lips may sink ships, but tight ones fail to inform, protect American public.
Author: N McLaughlin
Edition/Format:   Article : English
Publication: Modern healthcare, 2004 Dec 13; 34(50): 17
Database: From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
 
OCLC WorldCat
“Loose lips sink ships” : a history of rumor control in the United States
Author: Jeffrey Graham
Dissertation: Thesis (Ph. D.)—City University of New York, 2009.
Edition/Format:   Thesis/dissertation : Thesis/dissertation : Manuscript Archival Material : English