This was a present from my wife (don't ask!):
A coupla doorstep preachers knocked on my door on Christmas Eve, saying, "Hi there. We've got a message we'd like to share with you."
So I showed them the leprous-looking spots on my head and forearms, and said "...and I've got some Chicken Pox that I'd like to share with you..."
They both went deathly white and backed away from me, rapidly, their arms raised in a defensive position. The glue-on smiles were wiped from their face in a moment; all Christmas cheer instantly erased...
I kid thee not: they literally ran down our drive.
"Hey! What about my soul!" I shouted after them as they disappeared down the road, not even bothering with our neighbours.