To be stubbornly self-willed; to push aside restraints and go one’s own way. The analogy here, to a horse that catches the bit in its teeth so that the rider or driver has no control over it, dates from the sixteenth century. John Lyly used it in his Pappe with an Hatchet (ca. 1589): “But if like a resty iade [restive jade, or nag] thou wilt take the bit in thy mouth, and then run over hedge and ditch, thou shalt be broken as Prosper broke his horses.” The expression is used less often today and may be obsolescent.