If only it worked that well, even demons wouldn't repel those folk!
Just be like:
"Hey how are you?"
Jehovah witness: "Hello, do you know Jesus Christ our savior, I mean REALLY know him?"
you: "Yea, hang on...we're having a birthday party right now, would you like to come in?"
Jehovah witness: "..........we'll come back another time."
Its against their religion to party or celebrate anything, even their own birthday!