I like the one about not sweeping before bedtime. Sounds like it was invented by a man. The last thing you would want is your wife exhausting herself just before she has to perform her marital duties.

My personal superstition is to carry a picture of my first cousin once removed whenever I travel by air. He was in the RAF and was shot down over Germany on Christmas eve 1944. I know that he will keep whatever plane I am on from crashing!