cut of his/her jib, I don't like the

I don’t like his/her general appearance or manner. The jib is a triangular foresail, and in the days of sailing ships sailors often would recognize the nationality of a particular vessel by the precise shape of its jib. By 1800 or so the term had been transferred to human beings. In 1823 Robert Southey wrote, in a letter, that the likability of some individuals “depends something upon the cut of their jib.”