For JWs with at least a grain of knowledge:
I say: What is the biblical foundation for 1914? (Don't ever bring up 607 versus 587!)
He/she says: Nebuchadnezzar's dream where a tree was cut down and the King of Babylon turned insane.
I say: So when did the king of Babylon regain his insanity? During the 7 years or after it?
He/she says: Afterwards, of course.
I say: So If the King regained his insanity after the 2520 days then why have the nations, whom he symbolizes, not gained their sanity after the 2520 years but have only become worse?