Everything must be parallel, and if possible, symmetrical. My monitor must be in the middle of the desk, my desktop at the side must be parallel with the edge of the desk. The front of the keyboard must line up with the front of the desk.
All numbers must also be equal or in intervals of 5, although if it's between 60 and 70 it has to be 64.
I feel the need to dismantle and fix anything, even if it's just a pen. If I don't have something to dismantle with me, I have to break something.
If I'm on a computer, my mouse MUST NOT be making anything pop up. For example, when you make a post, and you scroll down to read the rest, hover your mouse over a post and it says "Post XXXXXX". I HAVE to move the mouse away from it to stop it doing that. Same with images and stuff.
Also, I hate walking behind someone if I'm alone, I either have to catch them up and talk to them, whether I know them or not, or walk really slowly so that they're far away.
Everything has to be stacked correctly. You can't have a large object on top of a small object, it has to make a pyramid, and if they don't line up, I have to turn them so they align.