Slippery post

Ok I know I saw it somewhere, and I thought I downloaded it, but I didn’t. I also cannot find it. there is a pugin called slippery post which does the opposite of adhesive.

I wish to make posts in a certain category only show up in that category. That is what this plugin claimed to do, and now I cannot find it. Can someone help me find it, or figure out a way to do it.

thanks