If the appsecret is set for the facebook app (this is the default)

Require AppSecret Proof for Server API calls:

This requires the application to submit a proof of app secret when it makes API
calls from a server.

The following code fails at the cgfb_me call

{cgfb_init}{* initialize facebook javascript SDK *}
{cgfb_login}{* provide a login button to facebook *} 

{cgfb_uid assign='fb_uid'}{* get the facebook user id *}
{if isset($fb_uid)}
  {* user is logged in *}

{cgfb_me assign="me"}{$me|@print_r}

{/if}

Fatal error: Uncaught OAuthException: An active access token must be used to
query information about the current user. thrown in
/home/eject/public_html/modules/CGFBApp/lib/php-sdk/base_facebook.php on line
1254

more information is available here 

https://developers.facebook.com/docs/reference/api/securing-graph-api/