Something that will....well, get a reaction out of any 'good' JW:
Point them at www.snopes.com and show them how many of 'their' urban legends, in fact, originated OUTSIDE their religion.
And, if that's not enough, visit an ex-mormon board.
Between the two sources, I think pretty much every single JW urban legend is covered.
But, of course, the JWs do always put their own spin on it.
Like the girls who go to have their fortune told, but the fortune teller can't work her magic because one of the girls is a witness. The 'angel protector' is actually common in ALL religions, but you gotta wonder, if the angel is protecting the woman in question, why is their so much suffering in the world? Applied to JWs, if the angels protect a sister from being raped in field service, why not protect an ENTIRE congregation from a bomb attack?
Doesn't make sense.