gistfile1.txt

// sfw endpoint
add_action( 'init', 'add_sfw_endpoint' );
function add_sfw_endpoint() 
{
  add_rewrite_endpoint( 'sfw', EP_ALL );
}

add_action( 'pre_get_posts', 'sfw_pre_get_posts' );
function sfw_pre_get_posts($query)
{
	global $wp_query;
	if (isset($wp_query->query_vars['sfw']))
	{
		$query->query_vars['tax_query'][] = array(
			'taxonomy' => 'post_tag',
			'field' => 'slug',
			'terms' => 'nsfw',
			'operator' => 'NOT IN',
		);
		if ( ! empty($wp_query->query_vars['sfw']))
		{
			$vars = explode('/', $wp_query->query_vars['sfw']);
			foreach ($vars as $i => $var)
			{
				if ($i % 2 == 0)
				{
					if ( ! $wp_query->is_singular() && $var == 'page')
					{
						$var = 'paged';
						if ($vars[$i+1] > 1)
						{
							$wp_query->is_paged = true;
						}
					}
					$wp_query->query_vars[$var] = $vars[$i+1];
				}
			}
		}
	}
}