jaywalk - Jays, like all relatives of the raven, are clever birds. Somehow, though, in the America Midwest, their name came to be applied to a stupid or simple person, the kind who might wander out into traffic without waiting at a corner for a signal. The word, which dates to about 1917, has nothing to do with the way the bird hops around.
discount - In ancient markets, prices were calculated with stones on a board. A seller with a flair for drama might have swiped some of those stones from the board, an act that a Roman might have called a discomputare, "taking away from the count." English borrows the term by way of the French d'escompte
pawn - The lowest, more readily sacrificed chess piece takes its name from its military counterpart, the foot solider - in Latin, pedonem, which also gives us, via Spanish, the word peon.
kit and caboodle - In eighteenth-century English slang, "the whole kit" referred to the totality of a person's possessions or the company he or she kept, as in "she brought the whole kit," or "he and his whole kit just showed up." On the American frontier, the phrase became "the whole kit and caboodle," the latter being a slang term meaning "crowd" - thus, "the whole bunch and whole bunch."
quiz - Originally, "quiz" referred not to a brief test but to a person whole looked strange or acted strangely. Jane Austen continued the sense of oddness when one of her characters asks, "Where did you get that quiz of a hat?" The current usage probably comes from the Latin quis?, the question word meaning "Who?"