What about throwing them a curve with the generation scenario; Ask them if they are bible students:of course you will get an affirmative on that. Then get them to read matt:24:34 and hone in on the point it says this gen. not these gen. not progressive gen. but THIS GEN. Then ask them to look up Matt.1:17,ask them when Abraham was born (the watchtower says 2018) then ask them when Jesus was born (the watchtower says 2BC) Matt.1:17 says their are 3 lots of 14 generations between Abraham and Jesus ,simple arithmatic leads you to the conclusion that a generation according to holy scripture is a mere 48 years ,so if the Watchtower was correct about 1914 the end should have occured by 1962 .Another generation on top of that would be 2010,still no armageddon,obviously the WTB&TS have stuffed up again
Have a good day
smiddy