OmNomNomify

Brighten up your web browsing with the Cookie Monster!
// ==UserScript==
// @name           OmNomNomify
// @description  Brighten up your web browsing with the Cookie Monster!
// @include        *
// @author         Zackton
// @version        1.0
// @namespace https://greasyfork.org/users/8935
// ==/UserScript==

setInterval(function(){start()}, 5000);

function start() {
    (function nomify() {
        var shapes = {
            "w_rect": ["tumblr_mohxt1V6a91svhqpoo1_500.gif", "tumblr_md0q05wMJb1rxis0k.gif", "tumblr_ml0nmjWpX41snjjivo1_500.gif", "CastDance_322x183.gif", "CookieDawn_322x183.gif", "Painting_322x183.gif"],
            "t_rect": ["CookieMonster-Sitting.jpg", "487961_10150955894571587_1215263686_n.jpg", "534767_10151516100086587_1790492047_n.jpg", "Static.jpg"],
            "square": ["cookie_monster.jpg", "935823_10151502554911587_1547641144_n.jpg", "902502_10151355606796587_45192127_o.jpg", "cookie-monster.jpg", "Cookie_250x250.gif"]
        },
            img_path = "http://downloads.cdn.sesame.org/sw/OmNomNomify/";
        
        function chooseImg(shape) {
            return img_path + shapes[shape][Math.floor(Math.random() * shapes[shape].length)]
        }
        
        function getShape(h, w) {
            return h === w ? "square" : h > w ? "t_rect" : "w_rect"
        }
        var imgs = document.getElementsByTagName("img"),
            img, h, w, shape;
        for (var i = 0, len = imgs.length; i < len; i++) {
            img = imgs[i], h = img.height, w = img.width, s = getShape(h, w);
            img.setAttribute("height", h);
            img.setAttribute("width", w);
            img.src = chooseImg(s)
        };
        return void 0;
    })();
};