app.js

(function($) {
  var plugin = $['ui']['autocomplete'].prototype;

  // store copies of the original plugin functions before overwriting
  var functions = {};
  for (var i in plugin) {
    if (typeof(plugin[i]) === 'function') {
      functions[i] = plugin[i];
    }
  }

  // extend existing functionality of the autocomplete plugin
  $.extend(true, plugin, {
    _create: function() {
      var self = this,
        doc = this.element[ 0 ].ownerDocument;

      functions['_create'].call(this);

      this.hintText = this.element.data('hint');
      this.searchText = this.element.data('searching');

      // set up the hint object
      this.hint = $("<div></div>")
        .addClass("ui-autocomplete-hint")
        .appendTo($(this.options.appendTo || "body", doc)[0]);

      // show/hide hint text on focus/blur
      this.element
        .bind("focus.autocomplete", function(event) {
          self._showHint(self.hintText);
        })
        .bind("blur.autocomplete", function(event) {
          self._hideHint();
        });
    },

    destroy: function() {
      this.hint.remove();
      functions["destroy"].call(this);
    },

    _search: function( value ) {
      this._hideHint();
      this._showHint(this.searchText);
      functions["_search"].call(this, value);
    },

    _response: function( content ) {
      this._hideHint();
      functions["_response"].call(this, content);
    },

    _showHint: function(text) {
      var text = $.trim(text);

      if (text !== '') {
        this.hint.text(text).show();
        this._resizeHint();
      }
    },

    _hideHint: function() {
      this.hint.hide();
    },

    _resizeHint: function() {
      this.hint
        // .outerWidth(Math.max(
        //  this.hint.width("").outerWidth(),
        //  this.element.outerWidth()
        // ))
        .outerWidth(this.element.outerWidth())
        .position($.extend({
          of: this.element
        }, this.options.position));
    }
  });
})(jQuery);

some.js

      $('#contact_search').parent('form').submit(function() {
        if (data.indexOf($('#contact_search').val()) < 0) {
          return false;
// Right here, I want to proc the _showHint function from the autocomplete extensions above.
        }
      });