Galumphing — to prance about in a triumphant manner. Lewis Carroll coined the word for Through the Looking Glass (1871) in “Jabberwocky,” apparently by blending gallop and triumph.
A pretty penny — a considerable profit, or a large sum of money. The expression came into the language in the 1700s. George Eliot used it in her famous novel, The Mill on the Floss (1860) in this sentence: “That watered-silk she had on cost a pretty penny.”
Chortle — another lovely word coined by Lewis Carrol and used in “Jabberwocky,” a poem in Through the Looking Glass (1871). Probably a combination of chuckle and snort. The current meaning is “joyful laughter.”
Blue-eyed boy — the current darling, or favorite. More used in Britain and Australia than in America, and often with a derogatory or envious tone of voice. It seems to have been coined by P.G. Wodehouse in Damsel in Distress (1919): “He’s the blue-eyed boy, and everyone else is an also-ran.” Perhaps Wodehouse saw The Blue-eyed Boy, a 1916 painting by Modigliani. The boy in the painting has a self-important expression that makes me want to smack him. Hard.
Let your hair down — to behave in a free or uninhibited manner. Letting one’s hair down was a common part of womens’ lives in the 1600s. The hair was normally pinned up and only let down for brushing or washing.
Give an inch, take a mile — make a small concession to someone who takes advantage of you. This expression was already a proverb in John Heywood’s 1546 collection, “Give him an inch and he’ll take an ell.” The use of “mile” dates from about 1900.