Living abroad for four years made me appreciate both how much English is spoken around the world, such that you have a very good chance of being able to converse with random citizens of other countries, and also how much more English is spoken by native speakers, such that you need to remember to speak more slowly and simply to minimize the misunderstandings that might crop up with non-native speakers. You don't realize how strange and complicated the language is, and how much it is constantly changing, until you find yourself trying to explain the meaning of certain turns of phrase. Eventually, you just try to speak basic textbook English, to make it easier for the people who are nice enough to spare you the pain of struggling along in their native tongue.
And then you come back to the States.
I came back, and was excited to be able to speak at will, to hear and use words with many syllables and hard-to-define meanings. I soon realized that in four years of trying to learn German and speak simplified English, parts of my English-speaking brain had gotten a little bit rusty. Even now, a year later, I sometimes find myself searching for a word, fumbling around in a dusty corner of my brain, thinking, "I know there's a word for that, now where did I leave it?"
And idioms. Idioms have proven to be just as tricky as words that had been put away for safekeeping.
Note to self: Having a "wandering eye" and having a "lazy eye" are two very different things, and one should avoid saying that someone has the former, when they actually have the latter.