Alright, I'll explain.
On Twitter you can follow whoever want. You can see what they post and reply to it, it's actually pretty cool. In this case Shane Carwin found it strange that he wasn't "following" his employer, The UFC, so he attempted to subsribe. He then remembered that he was a "follower" previously and realized that the UFC had removed him from their followers and blocked him from subscribing again.
Kind of a weird situation. To be honest, the guy who gets paid to run the UFC's twitter account probably accidentally clicked on Shane Carwin instead of someone above or below him... Would be awesome if they cut him... That would mean that Strikeforce could potentially have Duffee and Carwin