just for fun

konami.js

(function(w) {
    var konami = [38,38,40,40,37,39,37,39,66,65], n = -1;

    w.addEventListener('keyup', function(event){
        (n = event.keyCode == konami[n+1] ? n+1 : -1) == konami.length-1 && w.dispatchEvent(new Event('konami'));
    });

    w.konami = function(callback) {
        w.addEventListener('konami', callback);
    }
})(window);