So, as an explanation for why I had to run out and pick up lunch yesterday before the company-sponsored lunch (during a Day of Many Meetings), I said, "I keep kosher." And everyone seemed to perfectly understand what I meant. This is not an uncommon occurrence. It wasn't until today, however, that it occurred to me that it is a phrase that elides a lot of information, uses a word to mean something other than what it traditionally means, and includes a non-English word. Yet my coworkers were not at all confused.
The sentence seems simple. Three words. But only one of them -- "I" -- is straightforward. "Keep" does not usually mean "observe" in American English. "I keep kosher" is not like "I keep birds as pets" or even "I keep time for races" (though I guess it comes somewhat closer to the latter use of "keep").
And "kosher" is a concept that is first of all mostly unfamiliar, I would think, outside the Jewish world. I presume that if I had the same conversation with someone outside of an area that has a decent-sized Jewish community they might not recognize the word. The root means "appropriate";
Judaism 101 suggests "fit, proper, or correct" as definitions. Though "kosher" has made it colloquially outside the Jewish world, the actual details of what kashrut is are not widely familiar.
I'm not sure what specifically caused me to think about this, but there you have it.