What does it mean to ';stub your toe'; I think it is hitting any stationary object and wife does not?

I think it is bumping your toe on an inanimate object that you probably didn't see.What does it mean to ';stub your toe'; I think it is hitting any stationary object and wife does not?
Stub is used to refer to toes almost exclusively, don't ask me why. The dictionary definition defines it as hitting a toe on something. I have heard it used for fingers but rarely. I have never heard anyone say they stubbed their forehead on the range hood, for instance, or stubbed their knee, or that they stubbed a nail with a hammer. It means toes, just live with it.What does it mean to ';stub your toe'; I think it is hitting any stationary object and wife does not?
Tripping on an inanimate object, I don't think kicking the cat qualifies.