$(document).ready(function() {
   $('#post_author_name_field').click(function() {
       if($('#post_author_name_field')[0].value == 'Anonymous') {
          $('#post_author_name_field')[0].value = ''; 
       }
   });
   $('#post_author_name_field').blur(function() {
      if($('#post_author_name_field')[0].value == '') {
         $('#post_author_name_field')[0].value = 'Anonymous'; 
      }
  });
});