This trip to Japan was the first time I had spent a significant amount of time in a country where I did not speak even a bit of the local langauge (unlike previous trips to the UK, Australia New Zealand, Belize, Costa Rica, El Salvador, or Israel). Even in Egypt I could pick up little bits of Arabic with my knowledge of Hebrew.
That said, I was sometimes reminded of what my elementary school principal once said about himself, which is that "I have a good ear for languages." On this trip I finally realized what he meant: he was good at figuring out context.
(I had a nearly deaf friend in college who also was just so smart that she could almost always figure out exactly what was going on in a conversation because she could infer from context.)
One example was in the airport, where my Air Canada boarding pass didn't list my UsAirways frequent flyer number. I went to the counter and asked, and the person turned to his colleague and said a few sentences in Japanese. Hearing the words "USAirways" and "Star Alliance" I immediately knew what he was asking, and so said "Hi" (Yes), starling the individual who thought I did not speak Japanese. Well, to a good extent he was right.
(Title borrowed from William Safire, zicrono livroho)