Loose Lip Meaning
(idiomatic, often pluralized) The practice or characteristic of being overly talkative, especially with respect to inadvertently revealing information which is private or confidential.
Example: c. 1940, Slogan used by US government during World War II:
Loose lips might sink ships.
1985 June 3, Richard Schickel, "Cinema: Gliberated in Dreamland Fletch," Time:
In the classic dramas of private investigation, the cheeky quip is the tough guy's challenge to toughness. In Fletch the quick, smartly paced gags somehow read as signs of vulnerability. . . . Every minute you expect the hero's loose lip to be turned into a fat one.
1996 Aug. 25, Donald E. Westlake, "Tough Guys Don't Shut Up," New York Times (Retrieved 29 May 2011):
Poor fellow, he had "cemented my reputation forever as a guy who tells too much truth." . . . But his loose lip has ultimately worked out for him.