gistfile1.js

<script src="//code.jquery.com/jquery-1.10.2.min.js"></script>
<script src="/js/waypoints.min.js"></script>
<script>
$(function() {
	var promo = $('#promo'),
		speed = 500; //speed in ms
	
		$('.promo-hook').waypoint(function(direction){
			if (direction === "down") {
				promo.slideDown(speed);
			}
			if (direction === "up") {
				promo.slideUp(speed);
			}
		}, {
			offset: function() {
				return -$(this).height();
			}
		});
		
		$('#close').click(function(){
			promo.slideUp(speed,function(){
				promo.remove();
			});
		});
});
</script>