After all my time wearing the kilt, I still am amazed why it's OK for people to ask the question.

But it is part of wearing what we wear, so we might as well go with it.

I once even thought of printing up some sort of card to carry around just for that.

Maybe have just your name and e-mail on one side, and on the other something like:

What is worn under the kilt? Pick one:
A. Nothing - everything works.
B. Shoes and socks.
C. Only my wife knows.
D. It costs $100 to find out.
- - - well you get the idea.