My friend used to live in a village deep in the mountains back in the day, and they had a strange custom out there. In general, most of their sheds were located outside, but whenever someone was about to go inside, whether someone was inside or not, they would first have to say something like “I’m opening the door now” or “I’m coming in.”
It was said that the reason for this was because there was a strange person called ‘the shed hag,’ and if you entered a shed carelessly, you could run into her. If you inadvertently ran into her, she would attack you with her bared, yellowing teeth.
People used to whisper in the past that those who went missing were unlucky enough to be taken away by her. But while she was scary, it appeared that she didn’t like people, and so, if you called out before entering a shed, she would hide.
“She was feared as a type of mountain witch, but in reality was probably just a warning not to enter places suddenly, I think.”
These days my friend lives down in the city, but even before he enters his own bedroom he still has a habit of knocking and calling out first.