The NSFW tag works like the spoiler and Image tags together. So NSFW images are hidden until manually revealed.
Here is the problem, the Image itself still downloads automatically to the computer by default and could cause issues for some people (at work mainly) as the image goes into the Temporary Internet Files folder.
What we need is some sort of code that does not download until the reveal is clicked.
This is code for the NSFW tag:
<div class="spoiler"><div class="spoiler-top"><span style="color: #FF0000; ">{L_PRIME_BBCODE_SPOILER_SHOW} NSFW Image spoiler:</span> <span class="spoiler-title"></span></div><div class="spoiler-box" onclick="spoilerToggle(this);"><div class="spoiler-hidden">[img]{URL}[/img]</div></div></div>
Here is how the tag works:
[nsfw:3fsl9f5f]http://listicles.thelmagazine.com/wp-content/upload/cheesellama.jpg[/nsfw:3fsl9f5f]
[ NSFW ]http://listicles.thelmagazine.com/wp-content/upload/cheesellama.jpg[ /NSFW ]