Not such an interesting one this time, but:
- 空気を読む [kuuki wo yomu] (lit. to read the air)
- to read the situation; to sense the mood
Mostly I'm posting this because it came up in my Japanese lesson today and then again in the episode of Lucky Star (#20) which I watched this evening, and I like that kind of synchronicity.
Incidentally, in internet slang at the moment 空気を読めない is often abbreviated to 'KY', meaning somebody who can't sense a mood. The kanji pun 空気嫁 seems to have a similar meaning (though it comes from the imperative form of the verb rather than the negative potential).