British actress Sienna Miller has blamed a mild form of Tourette's syndrome for her string of foul-mouthed outbursts last year. The Factory Girl star - who sparked controversy by revealing she takes drugs because "they're fun" - famously upset Pittsburgh, Pennsylvania residents last October after drunkenly calling their city "S$%tsburgh" during an interview.

The 25-year-old insists the rants are the result of suffering from a form of Tourette's syndrome, a neurological disorder which is most often associated with the exclamation of obscene or derogatory remarks.

She says, "These things just come out. I think it might be mild Tourette's, not to insult people who have proper Tourette's, but I will say the most inappropriate things at the most inappropriate time to the most inappropriate person. Always. Guaranteed."

And Miller reveals she has a string of cheeky nicknames for other American states, explaining, "Massivetwos@#$s is Massachusetts. Connectic#$%t, or Connectibutt."