thump (one's) chest

To make an ostentatious display of one's dominance, superiority, and pride. Typically said of men. The manager likes to thump his chest and make a big show of his authority during our production meetings, but you'd be hard-pressed to see him doing any actual work around the office. The politician always makes a point of thumping his chest during press briefings, never missing a chance to brag about his successes in office.