Topic Tuesday #13 2012/10/16 "It's bad luck to be superstitious"

It's beginning to look a lot like Halloween around here. I see spider (the fake kind) and ghosts hanging in trees, and tombstones popping up all over the place. I'll talk more about All Hallows' Eve, next week. Today  being this is the 13th Topic Tuesday, let's chat about luck, specifically superstitions. Triskaidekaphobia is the fear of the number 13. It's one of a very long list, 530+, and it's particularly amusing. 85% of western culture buildings typically skip the 13th floor and by that same regard, have no negative numbers for floors below the lobby. Eastern cultures skip the number 4, 13, and 14 due to the pronunciation being similar to the word death in regional languages. There are a tremendous number of superstitions and general phobias. Some well placed and founded in genuine harm, but most, are irrational.  A black cat crossing your path causing you to jump out of the way, putting you under a ladder and dropping your pocket mirror all in the same motion would probably cause a superstitious person to lose their marbles.
There is no cause to believe these things, but they have become part of our culture.
Question:
What are you afraid of (irrational or rational)? Why?
What's your favorite superstition? Why?