$(document).ready(function(){  
   
      $("#nav > ul > li").mouseover(function() {
		$(this).find("ul").stop(true, true).animate({"height": "show", "opacity": "show"}, 600, "easeOutBounce");
 
		$(this).hover(function() {}, function(){
			$(this).find("ul").stop(true, true).animate({"height": "hide", "opacity": "hide"}, "slow");
		});
	});
	
function preload(arrayOfImages) {
    $(arrayOfImages).each(function(){
        $('<img/>')[0].src = this;
        // Alternatively you could use:
        // (new Image()).src = this;
    });
}

// Usage:

preload([
	'images/nav-home.png',
	'images/nav-menu.png',
	'images/nav-gallery.png',
	'images/nav-nutrition.png',
	'images/nav-about.png',
	'images/nav-contact.png',
	'images/nav-videos.png',
	'images/nav-news.png',
	'images/nav-comments.png',
	'images/nav-leave.png',
	'images/nav-map.png'
]);
     
 });