cheat.js

if ( window.addEventListener ) {
  var pressed_keys = [];
  var cheat = "38,38,40,40,37,39,37,39,66,65";
  window.addEventListener("keydown", function(e){
    pressed_keys.push( e.keyCode );
    if ( pressed_keys.toString().indexOf( cheat ) >= 0 ) {
      // User entered the cheat - do something HILARIOUS
      pressed_keys = []; // wipe the keys
    }
  }, true);
}