Gift of gab
the "gift of gab" is the ability supposedly given to one who kisses the Blarney Stone in Ireland. This is the ability to talk others into doing what you want.
In Tommy Boy, Chris Farley seeks to find the gift of gab his father had as a salesman. This gift of gab is illustrated by David Spades comment that Farley's father could sell a "ketchup popsicle to a lady in white gloves."