I feel rather embarrassed admitting how many Japanese words and mannerisms I have ended up inserting into my everyday vocab/behavior.... Though, in my defense, I end up interacting with other people more in Japanese than in English so, how can things not slip in? Most of my friends are Japanese, and if they aren't Japanese, they can speak it extremely well. When my foreign friends and Japanese friends mix, all speaking is done in Japanese because that way, everyone can understand each other. Anyway, excuses aside, the things I use the most on a day to day basis.
One of those funny things I started doing and didn't notice until a friend commented on it. I was calling my office to ask for a favor, and the friend I was with started laughing at me because as I said "thank you" etc, I started bowing as if I was talking to my supervisor directly.
Unko-suwari basically means "poop sitting" and is termed this way because it's the way you squat over a Japanese style toilet. Like many of my friends sit when waiting outside a venue for the next band to start, it's an easy pose to take when you're smoking a cigarette and drinking a beer. I just find it comfortable so I often take this position to talk to them or drink my own beer when waiting.
3. Kousoku, uchiawase, enkai, undoukai
Even when talking to non-Japanese-speaking friends, these words often come slipping out with absolutely no barrier. They are words I use all the time and sometimes saying their English equivalent would take longer or not hold the same meaning. Luckily, once you've worked in Japan for awhile, a number of these words become familiar to you, whether you speak Japanese or not.
kousoku: highway (here in Kochi, I need to take the highway if I want to get out of the prefecture quickly)
uchiawase: business meeting (used when meeting with teachers about lesson plans)
enkai: drinking party
undoukai: sports day
4. kankei nai
For whatever reason I felt like "kankei nai" needed it's own explanation. The phrase means "no relation" and in my opinion, it is the best descriptive phrase when talking about Japan (so very many things are kankei nai here). Because of this, I end up using it a lot while speaking Japanese and a lot while speaking English because, "it has absolutely no relation" is longer and doesn't hold the same weight to me as "kankei nai" does.
Just like a true Japanese, I have found that I picked up the "shark hand" move for cutting through a crowd of people, the "come here" gesture that looks like I'm shooing someone away, covering my mouth when I laugh, and pointing at my nose when referring to myself. There is truly no reason that I picked these up other than studying Japanese and the culture for far too long now.... However, I think I picked up the "shark hand" gesture and held onto it because of the sign language club I was taking part in last year. Holding up your hand so that it makes a T with your face means "excuse me/sorry" in sign language, and I've always been one to remember physical movements better then verbal phrases.