From Fukuoka Now
Some of these are pretty observant, others I don't quite agree with...
Ways to fake Japanese fluency
10. Upon hearing "ne", respond with "sou desu ne"
9. When asked a question, cock your head to the side and pull air through your teeth
8. Always carry a newspaper on the subway. Make a big production as you turn pages
7. If you want something repeated, rather than saying you didn't understand, say you weren't listening
6. If you don't understand the conversation, pull out your phone and leave the room with a convincing "moshi moshi"
5. If you notice someone making a grammatical or cultural mistake, correct them with "wareware nihonjin wa..."
4. Girls, memorize "kawaii", "iyada", and "baibai". You are now fluent
3. Interrupt people mid-sentence with "heehh~" or "uso!"
2. Learn a phrase regarding theoretical physics and mix it into normal conversation
1. Well, you just go study, you lazy X$%#@!
Number two would be difficult enough to learn, let alone pronounce properly. My advice?
1. If you travel a lot, take a few minutes to have a conversation with a local and pick up a few words of the regional dialect (even one or two words is fine). Then, incorporate those words into your next conversation.
Example - I was hitchhiking back to Kagoshima one weekend and was picked up by a martial arts sensei from Kumamoto. I asked him what the word for "very" was in Kumamoto-ben (taigena), and taught him the equivalent in Kagoshima-ben (wassee). If this is your first time reading about dialects... it's no wonder many Japanese can't even understand each other.
2. Find a set phrase you can use in almost any conversation. If you're flaunting a camera, learn "may I take your picture?" (写真を撮ってもういいですか？). Quickly run away after that to leave the impression of fluency.
3．Numbers three, nine, and ten from the list above are particularly observant - more important than just learning the vocabulary and grammar is displaying the correct mannerisms: using filler words to show you are paying attention (I still get looks when I'm listening quietly, as is my instinct); stating the proper transition phrase before beginning a conversation (shitsureishimasu when interrupting someone, otsu kare sama desu when passing a coworker, sumimasen or gomen nasai used properly for apologies).
4. The classic smile and nod.
5. Talk to kids, young kids. They're eager to speak with foreigners, and as your Japanese may be comparable with theirs, you'll probably be able to understand 90% of what's said. Don't speak English to them; you're teaching them something more important than a simple eikaiwa ever could: there are foreigners in this country who are here to stay, and we try to learn the language.