A number of years ago I ran into a group doing street work in downtown Seattle. One guy approached me and starting talking about 1914 and the end of the world. I asked him if he'd read any of Russel's books. He said no. I told him he should, as Russell said 1914 would mark the end of the world, not the start of the last days. He mumbled something about Russell predicting big things and the conversation ended.
A few years ago I asked two JW's at my door about Jesus not being mediator. He insisted that Jesus was mediator to everybody, I asked him to look up when they changed that and come back and talk to me. (He didn't).
I liked asking them a question like that as I think its possible (although unlikely) they may look up the answer and be forced to think about it. This isn't really working anymore as they just say "look it up on JWdotborg"