I sometimes talk to myself or read aloud when it's evening and I'm the only human awake in the house.
I sing along to Ozzy and other "hard" rock at work, when I probably shouldn't; we're supposed to be family-friendly.
I once started headbanging while listening to my iPod and working in my studio. I promptly stopped and wrote myself a note that it was probably a bad idea to do that when I had an acetylene torch in hand.
I automatically correct published authors' mistakes in my books, and correct my parents' grammar and word usage a lot; I used to describe unnatural sibilance on people's voices as "hissy esses" when I was a kid, and even in my early adulthood, they would use that term to describe it. I roll my eyes and tell them "Mom/Dad! The word is SI-BI-LANCE!" When they say "try and", I say "try TO", and when they say "anxious" when they mean "eager", I set 'em straight. Sometimes I do this with my boyfriend, or even strangers.
I believe everyone is psychic to some degree.
I used to read encyclopedias and dictionaries as a kid, and as such, I used to have such an extensive vocabulary. Now my speech is so boring. I need to pick up the habit again.
I was a huge bookworm as a kid; I was almost always found with a book in hand, and if there were no books, I would read newspapers, magazines, the TV Guide (when it was paper), and even labels. Now I don't read a lot of books, and I'm embarrassed by that.
When I was younger, I felt more at home among adults. Now I still feel like I have the mind of a sixteen year-old, despite being twenty-seven.
I talk to animals like they can really understand what I'm saying, and I believe even if they don't understand the words, they feel the emotions behind them.
I still like "Power Rangers".
I know I need to eat more vegetables, but I can't bring myself to unless they're tempura-battered or I have a craving.
I believe in cryptids, reincarnation, ghosts, alternate dimensions, mythical creatures, totem spirits, and there really are more things in Heaven and Earth, Horatio.
For the most part, I know myself very well; my dark side, my male side, my animal side, I know them all.
I don't like the horror genre, but horror films can catch my interest, and I generally take a look after I spend a lot of time psyching myself up. The one that actually scared me was "The Grudge". I got so paranoid after seeing it in broad daylight, I locked all the doors and windows. This lead to me locking myself out by accident. That was an adventure.
When I approach a highly-charged topic in serious discussions online, I start shaking, but my mind stays calm, even if people insult me. I can be nasty when I argue, and I'm embarrassed about that, too; I think arguments are supposed to be done with dignity, intelligence, truth and mild manners.
My biggest quirk has to be the fact virtually all the characters I've created for online RPs actually talk to me. They run commentary on my life; some got freaked out over a "100 Best Horror Films" special while I was perfectly calm -in fact, I'd enjoyed it-, and one (I still don't know who) asked me to close my bedroom door since they felt paranoid when my back was to it. Some commented on high winds while I was doing sixty miles an hour on the highway, some held a discussion on how they were like a boy band despite being Pernese, and more.
It's not an auditory hallucination; I really think it's crowded in my brain housing unit.
EDITED TO ADD: I prefer total darkness when I sleep, and I listen to soft music to keep my mind quiet so I CAN fall asleep. There are children's books under the bedside table, so I can read 'em and relax before bed.
I also still keep plushies on my bed, on my bookshelf, in storage, and I sometimes even bring them on trips and to the con. I leave books open in front of 'em so they won't get bored while I'm gone. ^n_n^