Poup này mình đã áp dụng thành công nên chia sẻ cho tất cả các bạn , code này không phải do mình viết ra nhưng mình sưu tầm trên mạng và mình chia sẻ thôi =))

style scoped='' type='text/css'> 
#fb-fanbox {display:none;background:rgba(0,0,0,0.9);width:100%;height:100%;position:fixed;top:0;left:0;z-index:99999;}
#fb-boxclose {width:100%;height:100%;-webkit-transform:translateZ(0);}
#fb-boxview {background:#fff;border:8px solid #FD4343;width:340px;height:230px;position:absolute;top:33%;left:37%;}
#fb-closebox {float:right;cursor:pointer;position:absolute;right:-1px;top:-2px;}
#fb-closebox:before {content:"X";padding:5px 8px;background:#FD4343;color:#fff;font-weight:normal;font-size:12px;font-family:cursive;}
#fb-boxlink,#fb-boxlink a.visited,#fb-boxlink a,#fb-boxlink a:hover {color:#aaaaaa;font-size:9px;text-decoration:none;text-align:center;padding:5px;}
</style>
<script type='text/javascript'>
//<![CDATA[
jQuery.cookie = function (key, value, options) {
// Pengaturan cookie
if (arguments.length > 1 && String(value) !== "[object Object]") {
options = jQuery.extend({}, options);
if (value === null || value === undefined) {
options.expires = -1;
}
if (typeof options.expires === 'number') {
var days = options.expires, t = options.expires = new Date();
t.setDate(t.getDate() + days);
}
value = String(value);
return (document.cookie = [
encodeURIComponent(key), '=',
options.raw ? value : encodeURIComponent(value),
options.expires ? '; expires=' + options.expires.toUTCString() : '', // use expires attribute, max-age is not supported by IE
options.path ? '; path=' + options.path : '',
options.domain ? '; domain=' + options.domain : '',
options.secure ? '; secure' : ''
].join(''));
}
// Dapatkan cookie
options = value || {};
var result, decode = options.raw ? function (s) { return s; } : decodeURIComponent;
return (result = new RegExp('(?:^|; )' + encodeURIComponent(key) + '=([^;]*)').exec(document.cookie)) ? decode(result[1]) : null;
};
//]]>
</script>
<script type='text/javascript'>
jQuery(document).ready(function($){
if($.cookie('popup_facebook_box') != 'yes'){
$('#fb-fanbox').delay(3000).fadeIn('fast');
$('#fb-closebox, #fb-boxclose').click(function(){
$('#fb-fanbox').stop().fadeOut('fast');
});
}

});
</script>
<div id='fb-fanbox'>
<div id='fb-boxclose'>
</div>
<div id='fb-boxview'>
<div id='fb-closebox'>
</div>
<iframe allowtransparency='true' frameborder='0' scrolling='no' src='//www.facebook.com/plugins/likebox.php?
href=Fanpage&width=402&height=255&colorscheme=light&show_faces=true&show_border=false&stream=false&header=false'
style='border:none;overflow:hidden;width:339px;height:200px;'></iframe>
</div>
</div>

<div id='fb-root'/>
<script>
window.fbAsyncInit = function() {
FB.init({
appId : 'FB APP ID',
status : true, // check login status
cookie : false, // enable cookies to allow the server to access the session
xfbml : true // parse XFBML
});
};
(function() {
var e = document.createElement('script');
e.src = document.location.protocol + '//connect.facebook.net/en_US/all.js';
e.async = true;
document.getElementById('fb-root').appendChild(e);
}());
</script>