The rules are simple, it can be anything you keep a secret or just don't tell people about it.
For instance, myself, I used to be so fascinated with every single aspect of the game back when I started Wowing, I would simply stare at things and /gasp
anyway, I set out to be the "first"(at least I thought so rofl) level 40 under to have all exaulted Alliance reputations and to have Old Ironjaw. It was a tedious, but fun grind and since I got it, I always keep OJ in my inventory next to my hearthstone, it's been my lucky talisman for 3 years already. I haven't told anyone in the game that yet.
Your turn! =)