If you live/have lived in Japan, have you picked up a local dialect (方言)? When I was living in Itami, Kansai-ben （関西弁）gradually became a part of how I spoke in Japanese. I never got to the point where I was splattering every sentence with localisms, but all of my *「超'」s (ちょう）were replaced with 「めっちゃ」's and 「やな」became a common sentence finisher for me.
Having returned to the States, it kind of goes without saying that my Japanese has been in decline, especially my conversational skills. Something else I've noticed, though, is that I've been losing my Kansai dialect. It's not that I don't understand it anymore, and sometimes a 「めっちゃ」or 「まじで」will slip unbidden into my speech, but for the most part when I have a chance to speak to people here, it's in standard, "Tokyo Japanese" （標準語/共通語）. My coworkers use it, and a lot of the Japanese people I've met here are from the Kanto area originally.
While there's nothing wrong with the standard dialect, there's something kind of nice about picking up a bit of an accent. I guess it kind of serves to further connect you to the place you live(d). I'm a little sad to have that slipping away.
* 「超」 is a slang-ish word these days used around Tokyo that means "very."
(Example: This cat is super cute!)
「めっちゃ」 is kind of the Kansai-regional counterpart.