strange code i found

[Keyser S?ze]

does anyone know what this goes to or why it is here, i found it in my navbar template

<script type="text/javascript">
<!--
function log_out()
{
    ht = document.getElementsByTagName("html");
    ht[0].style.filter = "progid:DXImageTransform.Microsoft.BasicImage(grayscale=1)";
    if (confirm('$vbphrase[sure_you_want_to_log_out]'))
    {
        return true;
    }
    else
    {
        ht[0].style.filter = "";
        return false;
    }
}
//-->
</script>

thanks