I'm guessing they're quickly blocking then unblocking people who follow. That's the easiest (only?) way to remove a follower.<p>I do this when I want someone to stop following me but I might still want to follow <i>them</i> or I don't want them realizing/caring they're not following me anymore or feel I'm blocking them entirely.
Since everyone seems to have uncovered the trick a new question stands: what happens to your following once the owner decide to go back and unblock everyone?<p>Enjoy the surprise in your TL :)
<a href="http://i.imgur.com/MJvfsdB.png" rel="nofollow">http://i.imgur.com/MJvfsdB.png</a><p>Gotcha.<p>Edit: And I wonder if they'll run out of API calls if enough follow it?