Guy convinces girl he's a vampire-werewolf hybrid
An unusual, but apparently effective pickup strategy. The guy was later charged with statutory sexual assault since he was 19 and she was 15. To prove to police that he was a genuine vampire/werewolf, he showed them his canine teeth. The police pointed out to him that "all mammals, including humans, have canine teeth."
German museum discovers its Monet is a fake
The clues: a retraced signature, it was painted over a drawing that was clearly not a Monet, and a "colourless substance" had been applied to make the painting look older.