@giulio_mattioli
Historians are undecided about this. One group proposes that it stems from medival religious modesty. Others say it may have to do with the three Holy Kings St. Ramsauer, St. Dobrindt and St. Scheuer. Also a certain archangel Mehdornicus is brought up in the scriptures to have coined this phrase.
It's a land of myths. 🤷♀️