I don't believe in luck or anything crazy like that, but I absolutely believe I can't sleep on a full moon. What weird things do you uncharacteristically care about? Ladders, mirrors, umbrellas, black cats...

Edit: I thought of another one. I do lots of races, and I often pick up my race shirt a few days before the race. I believe it's bad luck to wear your race shirt before you've completed the race. I will never ever wear the shirt to the race or before it.