请问下面的脚本能实现什么功能啊？

<script language="javascript">
function qqping_url_build()
{
 p=window.top.document.URL.indexOf("?");
 if(-1==p)p=window.top.document.URL.indexOf("&");
 if(-1==p)address="u="+window.top.document.URL;
 else address="u="+window.top.document.URL.substring(0,p);
 p=document.referrer.indexOf("?");
 if(-1==p)p=window.top.document.referrer.indexOf("&");
 if(-1==p)refer="r="+window.top.document.referrer;
 else refer="r="+window.top.document.referrer.substring(0,p);
 return address+"&"+refer;
}
document.write("<div style='position:absolute; left:0px; top:0px; width:0px; height:0px; z-index:0; visibility: hidden;'><img src='http://ping.qq.com/ping?" + qqping_url_build() + "' height='0' width='0'></div>");
</script>

哇，好好笑