Google and Facebook are using a X-Frame-Options in the HTTP response header to avoid the content being loaded in a iFrame.
The X-Frame-Options HTTP response header can be used to indicate whether or not a browser should be allowed to render a page in a or . Sites can use this to avoid clickjacking attacks, by ensuring that their content is not embedded into other sites.
Source: https://developer.mozilla.org/en/The_X-FRAME-OPTIONS_response_header
I don't think it is possible for you to override this setting.