I heard tell of a scammer who unknowingly called someone in law enforcement and tried to claim that if the victim didn't cooperate, they were going to get arrested.
I'm getting emails saying that my UK taxes are due. Dude, I think you're a little behind the times. There was a whole big mess about the US not wanting to pay UK taxes
Think I might have seen one once where the intended victim was a lawyer, who had a field day with nailing them on all the incorrect things and departments they tried to claim were involved