Spoiler :

After I read from other bloggers posting a review of the spoiler. I became interested. Then I tried, and failed. And do not try to find the cause of failure :p
But after looking around there I finally found the coding of the spoiler that I can use.

Well, for you are curious and want to try it, please follow the steps below:

Just copy this code.

<div>
<input style="margin:0px;padding:0px;" onclick="if (this.parentNode.parentNode.getElementsByTagName('div')[1].getElementsByTagName('div')[0].style.display != '') { this.parentNode.parentNode.getElementsByTagName('div')[1].getElementsByTagName('div')[0].style.display = '';this.innerText = ''; this.value = 'Sembunyikan'; } else { this.parentNode.parentNode.getElementsByTagName('div')[1].getElementsByTagName('div')[0].style.display = 'none'; this.innerText = ''; this.value = 'Tampilkan'; }" type="button" value="Tampilkan" /></div>
<div style="border: 1px solid #000000; margin: 10px auto; padding: 5px; background: #c9d2ed none repeat scroll 0% 0%; width: 500px;">
<div style="display: none;">
Isikan hal yang ingin kalian sembunyikan disini.</div>
</div>

Nb : you must change that red sentence with writing or pictures that you will hide.

For the result, you can see below...

You want to see what's in this box?

Just try it. Happy blogging :D