I've freaked out more than one JW like that. If I know it's one or a pair of them, I grab the copy of the Necronomicon we keep as a coffee table book in the 2nd living room and answer the door with "Hey, you're just in time! Did you want to sacrifice the goat to the great Cthulhu or just watch today?" I generally get either the gobsmacked "Uhhh... I'll leave you to that," or the one that completely misses it and says "Have you found Jesus?," which merits the response "Oh, you mean the hamster? Yeah, we just sacrificed him the to Holy Snake of Asgard we keep in the backyard."