Knock! Knock! First recorded in about 1936, this appears to have originally been an American catchphrase used by someone about to tell a dirty story. Then it came into use by someone entering a room without knocking. Perhaps it is from the old schoolboy joke "Knock! Knock! Who's there? Grandpa. Whaddya want . . ." But one writer claims it may come from the Porter's scene in Macbeth (Act II. Scene iii): "Knock, knock, knock! Who's there . . . Knock, knock! Who's there, in the other devil's name . . . Knock, knock, knock! Who's there? Knock, Knock! Never at quiet! . . ."
Straight from the shoulder. The expression means honestly, frankly, and to the point and derives from a boxing term of the mid-19th century. A punch straight from the shoulder was once made by bringing the fist to the shoulder and sending it forward straight and fast. Such undeceptive blows are quick, effective, and often to the point of the chin.
Figurehead. Ship figureheads are carved figures or busts attached below the bowsprit directly over the cutwater. They have great ornamental value, but no function whatsoever and the ships would sail just as well without them. The carvings do inspire pride and confidence among seamen, however, and lend prestige to ships. Thus, figurehead has been used for at least a century to describe "a person who normally heads an organization, who lends his good name to it, but has no real duties in it."
Give a damn. The above was originally "I don't give a dam," the expression probably brought back to England from India by military men in the mid-18th century. A dam was an Indian coin of little value. I don't give a damn is first recorded in America in the 1890s. Its most famous use was in Gone with the Wind (1939) when Rhett Butler tells Scarlett O'Hara: "Frankly, my dear, I don't give a damn."
Divan. Divan has an involved but logical history. Originating as a Persian word meaning "a brochure," it came to mean, in order: "a collection of poems"; "a register"; "a military pay book"; "an account book"; "a room in which an account book was kept"; "an account office or custom house"; "a court"; "a great hall"; and finally, by 1597, "the chief piece of furniture in a great hall"!