I can't believe this thread. I've got OCD BAD. I've been doing that sidewalk thing my entire life. It took me a long time to realize that it wasn't normal. When I was a kid, if my mom tried to put my books away in my school bag, I'd FREAK, dump them out and do it again if they weren't perfectly in order.
When I get out of my Jeep, I press the lock button on my key chain 4 times. 4 time to unlock... I have it rationalized in my head that it's a precaution to make sure the button is working so no one will be able to rob me, or I won't end up lifting the handle with it still being locked. Riiiiight. I have issues with things being in fives or in even numbers. Eating candy, peanuts, or whatever can be stressful. I won't even get started on what I'm like with public restrooms. I don't think I'm a mysophobe or anything, but it certainly comes out when I'm in there.