A straight as in a straight flush in poker is attested from c.1840. To take an alcoholic drink straight or straight up, without a mixer, water, soda etc, is first attested in America from the 1850s. Straight as in the home straight, the last part of a race dates from c. 1860. Straight, as in a straight man, juxtaposed with a funny man, is American vaudeville jargon from the late 19th century. Straight as a synonym for heterosexual, dates from c. 1940 and is, presumably, the opposite of the now frowned upon ‘bent’. To go straight and cease criminal activities is slang from the early 20th century.