For me, the common things:
- I can't stand open doors.
- Spelling and grammar mistakes, I always bring them up when noticing them.
- I can't leave things unfinished.
- I always want to stop reading at the end of a chapter when reading a book, ending in the middle of a chapter is not an option to me.
- If I sorted out things in a certain order or system, I need them to stay in that order. For example, I sorted my Pokemon toys in boxes per generation, and I sorted the drawings I make of my girlfriend and me in chronological order, and way more things.
- I always save twice in games.
- For multiple things, I want an even and not an odd number.
- When I think about something I'm curious about, I can't let it go and have to look it up to let it go.
- The last song I listen to on a day HAS TO be a Bon Jovi song, usually either "Bed Of Roses" or "It's My Life".
I won't claim OCD, because I've never been diagnosed with it. Sure, there are moments when I think I might have it, but when I look here in this thread, I see that plenty of my habits are normal.