The Clinging Vine (1926)

Mannish ultra-efficient A.B. is the real force behind the Bancroft paint business. But on a weekend house-party when she overhears the boss's grandson Jimmy's unflattering opinion of her lack of charms, she's hurt. Jimmy's grandmother takes her under her wing, makes her over, and teaches her to flutter her eyelashes and only say the two phrases to win a man: "Do go on!" and "Aren't you wonderful?". And Jimmy falls hard, not knowing his darling girl is the dreaded A.B. But can A.B. maintain her girlish guise while setting Jimmy on the right track to financial security and a proposal?