View a sample here: http://jsjohnst.github.com/konami.html

geek.js

window.addEventListener && window.addEventListener('keydown', function(e) {
	this.keys ? this.keys.push(e.keyCode) : this.keys = [e.keyCode];
	if(this.keys.toString().indexOf("38,38,40,40,37,39,37,39,66,65") >= 0) {
		var audio = document.createElement("audio");
		audio.src = "http://geek.thinkunique.org/wp-content/vid/tmnt.mp3";
		audio.play();
	} 
}, true);