The main reason I hate this question when I'm away from work and work related contexts is that my company is all I talk about and think about for 99% of my time. And sometimes its really nice to have a small break from it. Also I know that once I start enthusing about it peoples eyes will be glazing over.

I certainly hate the idea of "normals" too - and I can easily explain what we do and am more than happy to if you are really interested. Just be sure you are because you might get quite a detailed and passionate answer.