Toggling dropdowns using jQuery, with binding and unbinding
First, regarding readability, I suggest changing the following names:


$dropdown -> $content
.toggle (class) -> .togglable
.toggle (namespace) -> .toggling
.isOpen -> isToggleOpen


On the other hand this can be achieved with reduced code (and less internal working impact), with only one event binded:

var $togglables = $('.togglable-content');
$(document).on('click.toggling', function (event) {
  var $target = $(event.target),
  $content = $target.siblings('.togglable-content');
  if (!$target.hasClass('isTogglableOpen')) {
    $togglables.not($content).removeClass('isTogglableOpen');
    $content.toggleClass('isTogglableOpen');
    return false;
  }
});


Here is the modified fiddle.