Say you are developing a website for a hotel which is already on Tripadvisor.(example). Now you know it's not good idea to fill reviews from hotel guests in your own page since it's better to rate hotel on Tripadvisor. I'm coming with a excellent idea by this you can allow your guest to fill the Tripadvisor rating form in your website only! And yea no plugin no addons !

see just using the script as bellow and add your url(in var iframesrc="pageurl") of the page your want to show

  <script type="text/javascript">

      var iframesrc="your page url will be gone here" 

    //You may change most attributes of iframe tag below, such as width and height:
    document.write('<iframe  src="'+iframesrc+'" width="650px" height="1710  marginwidth="0" marginheight="0" hspace="0" vspace="0" frameborder="0" scrolling="no" ></iframe>')

          </script>

Now put this excellent script in between your body tag and see the magic on live preview :)