Have some fun and do what I saw Dave Naylor doing a few months back
Dave's blog (you will have to search his blog for p-u-s-sy as the forum removes this word)

Include certain words on your feed that will mess them up, like Viagra, porn or pus@y (obviously he wasn't worried about these terms appearing on his blog). You could even serve a different rss feed to them if you can identify there ip address.