A friend's recent tweet reminded me of one of my strange tics: I generally highlight text as I read a webpage by double-clicking on it. It's not necessarily what I'm reading at the moment (I usually concentrate my clicking around the middle of the page), and I generally highlight and unhighlight repeatedly which I'm sure annoys people who know me in real life. Sorry.
I also count steps when I'm going up or down stairs, though I understand that one is a little more common. Plus, I have somewhat complicated rules about how I step on and over cracks and lines on the ground, but I won't bore and confuse you with those here on my blog.
I don't mean to talk (solely) about in which ways I'm weird: I like to ask other people what their idiosyncratic or OCD tendencies are. So what about you? I've had friends who must close any open cabinet doors in a kitchen, who crack their fingers in a specific way at specific times, or who always try to set their alarm clock to times that are palindromes. OK fine, that last one was mine again. But what are yours? What are the weird little things you do for no good reason?