Home in Norway we have a few, the first one that springs to mind is that if you whistle it will rain, at least according to my grandfather.
Earlier people would put out porridge to our equivalent of santa so that he would be happy and not torment the animals and cause all kinds of trouble on the farm.

We have one knife related too: it was this really good blacksmith where I come from that they say hardened his blades in water from a lake with a drowned man and he could only do it in the moonshine of a full moon. Might be something to try for the custom makers