How can I create a new route/menu in Drupal that doesn't automatically render a navigation link?

I'm trying to create a simple page callback in Drupal that doesn't show up in the Navigation menu.

I have a module named `helloworld`.

The `.module` file contains the following

```
function _helloword_page_callback()
{
    return array('#markup'=>'The quick brown fox says hello, and the lazy dogs thanks you
    for following conventions.');
}

function helloworld_menu()
{
    $items['helloworld'] = array(
      'title'               => 'Hello World',
      'page callback'       => '_helloword_page_callback',
      'access arguments'    => array('content'),
      'type'                => MENU_CALLBACK
    );
    return $items;
}

```

This successfully exposes a URL on the site of

```
http://example.drupal.com/helloworld

```

**However**, I'm still getting a link in the left hand (Bartik) navigation menu, despite the use of

```
'type'              => MENU_CALLBACK

```

So, why isn't this working? Am I configuring the Menu item correctly? A more likely question: How am I misinterpreting the use of the menu type constants/system? Are there additional caches to clear that 

```
drush cc all

```

wouldn't take care of? What other steps can I take to debug this?