I'm sorry, but 'joking' about blowing up something ANYWHERE in 2010 that is in earshot of another person (either physically or digitally) will likely get you at

I'm sorry, but 'joking' about blowing up something ANYWHERE in 2010 that is in earshot of another person (either physically or digitally) will likely get you at least a mild amount of attention from the authorities. My question however is did the authorities have someone report this to them, or were they proactively monitoring twitter for such? In my interactions with federal level law enforcement, it seems that their proactive monitoring is poor at best.