It's a conspiracy! A coverup! Obama was assassinated and replaced! Only FOX News knows the truth, Wake up Sheeple! It's obviously the Socialist Democrat Facist corporations plot to institute a puppet government to take over America.
It would have been better if the hackers posted some satirically extremist views that Fox can be said to endorse, and see if anyone noticed the difference, something like "Obama's failure to deal with illegal immigrants is leading to a second civil war. America must prevail against the communist Hispanics and Mexicans"
Or simply, "We are _____ and we have hacked Fox News' Twitter feed. We were going to write some horrible, insane, racist things, but realised we couldn't beat the crap that is aready posted here."