I discovered this in Lent and meant to get it posted here after Pascha, but forgot till now.
I remember sometime in Lent, I think at a meal after PreSanctified, chatting with Gavin Campbell about his encounter with a JW while waiting for a bus. Maybe we can get someone to post that anecdote in the comments here.
I have Fr. Lawrence's "Paschal greeting to JWs at the door" which I will post in the comments eventually. Feel free to add your own amusing tales there as well.
But I don't know if anyone can top this one about SF writer Tim Powers on a Catholic blog:
Powers, incidentally, is the author of The Drawing of the Dark, whence the immortal quote "If but we Christians have our beer/ Nothing's to fear."