Overwatch players are practically conditioned to react to McCree’s ultimate: if you hear “IT’S HIGH NOON” mid-match, you either quickly survey the area and run for your life, or you die. The sound cue is supposed to be useful and informative.
...unless of course someone starts abusing it. Nigma’s Vidya Channel took McCree’s sound clip and started playing it at random intervals during real matches, just to get a rise out of people. The result is pretty funny:
Ha. Can you really get mad, though? Even McCree’s voice actor allegedly does this while playing Overwatch: