Whoever came up with that deserves credit. Entirely lovely and harmless “superstition” as far as I can tell. No one is hoping for rain so they won’t be disappointed, but everyone has that line (“lucky it’s raining on your wedding day“ or whatever) ready just in case.

I wonder if there are other white lie kinda pro-social quips like that

It’s a free ride, but you already paid?

Like something about cutlery