I've got an aunt who moved to Munich about 20 years ago. I don't get to visit much, but I've crashed with her a couple of times. It's been about 15 years since I last had to demonstrate proficiency (gah! its been that long!) but my reading of the language has held up from singing German choral music (damn German choir directors!).
Downside is I look German enough and am familiar enough with Munich that I get into real trouble... people seem to think I know what I am doing!
My gaffes in Germany, though were in English. Some of my aunt's friends asked me how I was doing (having just gotten off the plane the day before) and I answered that my internal clock was "out of whack." They didn't know that phrase, so I changed it to "screwed up." Well, apparently they have learned most of their American slang from our military... and they were quite horrified at what they thought I had been doing. Thankfully my aunt was there and quickly translated the intended meaning of my slang.
Moral of the story... don't take short cuts in speaking with foreigners (or if you are the foreigner)! If only Sarah had learned.