1. About as loose-lipped as a Swiss banker —Harold Adams
2. Another person’s secret is like another person’s money: you are not so careful with it as you are with your own —Edgar Watson Howe
3. As secret as the grave —Miguel de Cervantes
4. Close up like a cabbage —John Andrew Holmes
5. Close up like a fist —Anon
6. Covert as a brass band —George F. Will
7. Fondles his secrets like a case of tools —Karl Shapiro
8. Furtive as a chipmunk —R. V. Cassill
9. Hide … like a disgrace —George Gissing
10. In the mind and nature of a man a secret is an ugly thing, like a hidden physical defect —Isak Dinesen
11. Lurking like a pilot fish among sharks —Speer Morgan
12. Move … like a rodent, furtively —John Phillips
13. Peered out (into the corridor) as stealthily as a mouse leaving its subterranean hole —Donald Seaman
14. (My face is an open secret but in my letters I) perform like a true diplomat, cunning and sly —Delmore Schwartz

    See Also: CLEVERNESS

15. Private and tight as a bank vault —Marge Piercy
16. Secrecy as tight as a bull’s ass in fly time —Stephen Longstreet
17. Secret as silence —Babette Deutsch
18. A secret at home is like rocks under tide —D. M. Mulock
19. Secret operations [by a government] are like sin; unless you’re good at sinning, you shouldn’t do it —George Kennan, CBS/TV, March 31, 1987
20. Secrets are like measles: they take easy and spread easy —Bartlett’s Dictionary of Americanisms

    Now that measles is controlled by vaccine, a virus or the common cold would probably be a more appropriate point of reference.

21. She has a mouth like a padlock —Graham Greene
22. Sneak away [for an acceptable, honorable activity] … as furtively as if he were stealing to a lover’s tryst —Edith Wharton
23. Stealthy and slow as a hidden sin —Stephen Vincent Benet See Also: SLOWNESS

button one’s lip To keep quiet or silent; to keep a secret; also button up and button up one’s face or lip. The expression has been in use since 1868.

hugger-mugger Covert or clandestine behavior, secrecy, furtiveness; confusion or disarray. This expression, possibly derived from the Middle English mokeren ‘to conceal,’ appeared in Shakespeare’s Hamlet regarding the manner of Polonius’ burial:

Although the expression maintains its furtive connotation, hugger-mugger now more frequently carries the meaning of jumbled confusion or disorganization, a meaning it assumed because clandestine activity is often hurried and haphazard.

in petto Undisclosed, kept secret; private, in one’s own thoughts or contemplation. This expression is Italian for ‘in the breast.’ Citations dating from the 17th century indicate that in petto is applied almost exclusively to affairs of church or state.

little pitchers have big ears An exhortation or reminder to guard one’s tongue because children may overhear words not intended for their ears. The handle of a pitcher is sometimes called its “ear.” Thus, pitchers have ears is a pun on ears, and is analogous in meaning to walls have ears. This expression appeared in print by the mid-1500s; the later addition of little limits the kind of listeners to children.

mum’s the word Remain silent; do not breathe a word of what was just said. Shakespeare conveyed this meaning in Henry VI, Part II:

This expression may have derived from the m-m sound, which can be produced only with closed lips. The phrase is particularly commonplace in Great Britain.

on the q.t. Secretly, surreptitiously, covertly, clandestinely, on the sly. Q.t. is simply an abbreviation of the word quiet in the original expression on the quiet.

skeleton in the closet A family secret or scandal kept concealed to avoid public shame and disgrace; any confidential matter which, if revealed, could be a source of embarrassment, humiliation, or abasement. Though popularized in the writings of William Thackeray (1811-63), skeleton in the closet is reputedly based on an earlier legend that tells of a search for a truly happy person, one free from cares and woes. After such a person had apparently been found, she opened a closet and exposed a human skeleton. “I try to keep my troubles to myself,” she explained, “but every night my husband compels me to kiss that skeleton.” The skeleton, it seems, was that of a former paramour whom her husband had killed.

A British variation is skeleton in the cupboard.

sub rosa Under the rose—in secret, privately, confidentially. Attempts have been made to trace the origin of this phrase to classical times; however, the OED states that it has Germanic origins. In Germany, and later in England and Holland, it was a common practice to paint or sculpture roses on the ceilings of banquet halls. The rose was a symbol reminding the revelers to watch their words. The phrase appeared in print by the mid-16th century. The English version under the rose is also heard.

under one’s hat Secret, private, confidential; between you, me, and the lamppost; usually to keep something under one’s hat.

Although the exact origin of this expression is not known, perhaps at one time the space under a person’s hat was literally used to conceal things. Use of the phrase dates from the late 19th century.

walls have ears An admonition to be discreet in speech, implying that privacy is never certain and that no one is to be trusted. The expression is often linked with the so-called auriculaires of the Louvre Palace, tubes within the walls by means of which Catherine de Médicis reputedly learned of state secrets. There is no evidence, however, that the phrase actually owes its origin to these contrivances. A similar concept and personification appeared contemporaneously in Heywood’s Proverbs (1562):