I believe that poison ivy/oak can get ‘into your blood’ and spread that way, or even reoccur later.
But I know that doctors are pretty convinced it can’t. I still believe it though because it fits my experience better than what the experts say.
What crazy things do you believe, even though you know better?
If I say something (in particular) hasn’t happened, and I don’t want it to, I say “knock on wood” because I have this nagging suspicion like God has a sense of humor and would make it happen just because I said it wouldn’t. Knocking on wood, or saying that phrase, has no effect on anything but I still say it.