Well,
I only have them at night, for some strange reason.
Whenever I look at my digital clock (when I'm in bed) the numbers can't add up to 13. If they do, I have to keep looking away and back again until it changes. I also have this before-sleeping ritual where my slippers have to be the same angle to the bed, and my study chair has to be 90 degrees to the foot of my bed, with my dressing gown piled on top of it neatly. I also have to say this phrase many times over, making sure that I don't say it 6, 13, 14 or 23 times (and preferably not a multiple of 2). And when I say good night to my parents, I have to say the exact phrase perfectly. If I mess it up, I have to say it again twice, to make sure I don't say 2, 4, 6 (or any multiple of two) times.
If I don't do these things, I have this weird feeling that something bad will happen the next day. It's kind of irritating.