Haha. My embarrassing gaming habit... is swearing! Much like everyone else. Thing is, I do it a lot. Sometimes it feels like I don't realize that my enemies aren't real people...

Once while playing a racing minigame, one of the other racers shot my character with a blast. I started swearing loudly at the AI, like "WHY THE F*** WOULD YOU DO THAT, YOU ****!" or "I F***ING HATE YOU, *****!" Honestly, swearing is a habit of mine, but it tends to take on an extreme form when I get into a good game.
I also tend to talk to myself a lot, but usually in my head. Sometimes I debate which way to go with myself, for example. I find it easier to think of solutions when there's another... person... to talk about it to.