function kcommand(func, cmd) {
if (!(func instanceof Function)) return;
var kc = {};
kc.func = func;
kc.cmd = (typeof(cmd) == "string" || cmd instanceof String) ? cmd : '|38|38|40|40|37|39|37|39|66|65|';
kc.count = 0;
kc.input = '|';
kc.up = function(event) {
event = event ? event : window.event;
if (kc.cmd.indexOf('|' + event.keyCode + '|') == -1) {
kc.input = '|';
return;
}
kc.input += event.keyCode + '|';
if (kc.input.indexOf(kc.cmd) != -1) {
kc.func(kc.count);
kc.count++;
kc.input = '|';
}
}
if (document.attachEvent) {
document.attachEvent('onkeyup', kc.up);
} else if (document.addEventListener) {
document.addEventListener('keyup', kc.up , false);
}
}

function display(count) {
    if (count % 2 == 0) {
        // if even
        $('body').find('div.secret').css({visibility: "visible",display: "block"}).show();
    } else {
        // if odd
        $('body').find('div.secret').css({visibility: "hidden",display: "none"}).hide();
    }
}

$(document).ready(function(){
    kcommand(display);
});