"add strength," 1941, from college slang, from beef (n.) in slang sense of "muscle-power" (1851).
"dirty look," by 1972, perhaps from Hawaiian slang.
"training station for recruits," by 1941, U.S. Marines slang, said to be from boot (n.1) as slang for "recruit," which is attested by 1915 and supposedly dates from the Spanish-American War and is a synecdoche from boots "leggings worn by U.S. sailors."
"mean, petty, unprofessional," 1906, from baseball slang for the small-town baseball clubs below the minor league where talent was developed (by 1903), from bush (n.) in the adjectival slang sense of "rural, provincial," which originally was simple description, not a value judgment.
1942, American English slang, the first element probably a nonsense reduplication of suit (compare reet pleat, drape shape from the same jargon).
by 1942, noun ("a cowardly escape, an evasion") and verb ("sneak off, escape, give up without trying"), American English slang, perhaps from cop a plea (c. 1925) "plead guilty to lesser charges," which is probably from northern British slang cop "to catch" (a scolding, etc.); as in cop a feel "grope someone" (1930s); see cop (v.). Sense of "evade an issue or problem" is from 1960s.
1947, RAF slang for "navigational instruments;" later extended to any sort of apparatus that operates in a sealed container. Especially of flight recorders from c. 1964.
"important person," 1929, American English, from Prohibition-era gangster slang; earlier in the same sense was great shot (1861). Ultimately a reference to large type of gunshot; see shot (n.).
