Unlucky for some

The fear of Friday 13th is quite irrational but still grips the popular imagination - no-one wanted to announce their engagement in today's Telegraph.  I once read a long exegesis (in pretending to be editorial) in The UB Post, outlining all the various theories as to how it arisen before concluding it was all bunkum. 
Ten years ago, before I had become acquainted with The UB Post, let alone read this piece, I asked as to the origin of why Friday 13th is considered so unlucky.  One of my group said, "It's because of a popular film franchise."  R-r-right.  Had the 'faceslap' meme been available then, that would have been an appropriate time to use it.