spoiler

BBCode
[spoiler={TITLE}]{TEXT}[/spoiler]

HTML
<div style="padding: 3px; background-color: #FFFFFF; border: 1px solid #d8d8d8; font-size: 1em;"><div style="text-transform: uppercase; border-bottom: 1px solid #CCCCCC; margin-bottom: 3px; font-size: 0.8em; font-weight: bold; display: block;"><span 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.innerHTML = '<b>Spoiler: </b><a href=\'#\' onClick=\'return false;\'>hide</a>'; } else { this.parentNode.parentNode.getElementsByTagName('div')[1].getElementsByTagName('div')[0].style.display = 'none'; this.innerHTML = '<b>Spoiler: </b><a href=\'#\' onClick=\'return false;\'>show</a>'; }" /><b>{TITLE}: </b><a href="#" onClick="return false;">show</a></span></div><div class="quotecontent"><div style="display: none;">{TEXT}</div></div></div>

Example:
[spoiler=Title]Content.[/spoiler]