Why is Twitter's new CEO Linda nicknamed 'Velvet Hammer'?

Linda Yaccarino, Twitter's new CEO who left her advertising job at NBCUniversal, is nicknamed the 'velvet hammer' in the advertising world. A report by WSJ said that Linda got the nickname for her "hard-nosed but fair" negotiating style. Advertising tycoon Sir Martin Sorrell described her as "very effective", adding: "She's probably just what clients need to establish trust and confidence."