This is Brozo the Creepy Clown, a television host on the Spanish language Televisa network. Apparently he gets very upset when people impersonate his co-host Marissa Rivera on Twitter. So upset in fact, that he threatens to come after them.
According to Boing Boing, the threatening part of Brozo's message translated to something along these lines:
We know about you. We're very close to you (we're on to you). Now you've really fucked yourself.
Update: Some readers familiar with the events and the show are noting that there are some things worth keeping in mind: Brozo feels that his co-worker is being endangered and his message can be interpreted to imply legal threats rather than something more sinister.