Any hide hack mod for wordpress?!?

Just wondering…

Is there any hack or mods for wordpress 2.0 and up that will hide a content of a post until the logged in member replys to the post?

You would wrap some content (picture, answer… or whathaveu) inside a bbcode such as [hide] … [/hide] and anything inside it will be hidden to the member until they reply to the post to see the hidden content.

The idea is just like Unreal’s Hide Hack mod for invisionboard.