born yesterday, not (I wasn’t)

Not naive; more experienced than one might think. Already a popular saying by the early nineteenth century, it appeared on both sides of the Atlantic. “I warn’t born yesterday,” said Thomas Haliburton’s Sam Slick in one of his Wise Saws (1843). Approximately a cen- tury later Garson Kanin used the phrase for the title of a Broadway play that became extremely popular, as did the later (1950) film version. In both, actress Judy Holliday played the quintessential dumb blonde who, despite seeming unsophistication, is graced with enormous good sense.