2 Things I learned from Japanese

The Japanese have two incredibly useful expressions.

One is 'Ah so', and it works wonders for filling up any awkward silences when you can't think of a suitable reply.

The other is 'un'. Which is more of a grunt, really.
It means yes.
It's not a slang term or anything of the sort, it's a totally accepted and widely used word.

I use these two all the time. A well-placed affirmative grunt can do wonders to a conversation. You can let a conversation die a slow death by pulling the sound out a little, and ending it on a falling note. If you, hovever, vigorously exhale the 'un', while keeping the tone flat, maybe nodding a little as the occasion demands, you can participate (or create the impression of participating) in a wide range of conversations, without descending to something as crude as actual words. Throw in a thoughtful 'ah so' or two, and you are set for 90% of life's conversational challenges.