make a grandstand play
1. In sports, to perform any excessively showy action or maneuver during play so as to impress or entertain the spectators. Originally specific to baseball, it has since been extended to any sport. Rather than shoot the ball and secure an easy two points for the team, she decided instead to make a grandstand play by trying for a slam dunk.
2. By extension, to act or behave in an excessively dramatic, showy, or ostentatious manner; to show off. Our manager is more concerned with making a grandstand play for the CEO than effectively running the office.