Hide and show part of post with comments

Hello,

I know there are a lot of plugin to hide part of a post between balise like <hidepost> </hidepost>.

But, as we can see on some forums, I would like to know if exists a plugin with the same feature that shows a hidden part of the post, but after posting a comment.`

Until the visitor post a comment, a part of the post is hidden. And as soon as he comments, the hidden part of the ppost is displayed, as a gift. No indication is shown about this process for the user.

I would lke the fact to comment is the “show process” but we could expect others things, as rss…

Do you know if a such plugin exists ? I didn’t found it until now. Just a few that show the hidden part after registering. And I would like only “post a comment”.

Thank you
John.