On the original 196 on the R site the only rule was to post before you leave. Because people are bad at naming things they started just titeling things 'rule'. It then became a part of the culture and more creative people started incorporating the word 'rule' in the title in more creative ways. When we switched to this site it became one of the unenforced rules to have the word in the title.

People put "rule" in their post titles to show they are justfollowing the rules by posting while they're in the sub