In many meme posts the author will write a title of the form “______ rule”. But looking at the context of whatever is posted, it never seems to be a use of the word “rule” as traditionally defined, not even a rule of the internet (or at least not one I’m aware of). Tried looking on Urban Dictionary, but it didn’t help. Is there any meaning to this use of the word “rule” in titles or is it simply an imitative fad?