Intellectual doesn't have to be the meaning of life. Talking about food can be interesting and thought provoking.

For example I have had some good conversations with people at work about food and more specifically cooking, and been given some great tips - this is a good conversation.

Another good topic that comes to mind was one talking about driving licences, problems and differences between Japan and Australia. We were both surprises - I was surprised that Japanese driving licences need to be constantly renewed in a long and painful fashion thats there to raise revenue, and they were surprised at the ease in which I can renew my licence (simply pay the money and get photo taken at one of many "service" locations) and can opt for a 10yr licence if I wish.

Edit: Its coming up to the bonenkai time of year, take note of what others are talking about and bring it up here. Should be interesting.