what else could I say??

[Rampant Lion]

Honestly, I don't understand why people get offended when asked this question. Now, I know every situation is different, but I would first assume that if I was asked "What do you wear under that?", the person asking the question isn't asking what I, personally, am wearing under my kilt, but is actually meaning "What does one wear under the kilt as opposed to pants?" And honestly, is that not a valid question?

Oh, I know most people probably ask because they've "heard" what's not worn under the kilt, but they probably just want to know the truth of the matter. Perhaps they think that's there's a special garment to wear under the kilt, or what is more widely worn, possibly due to comfort or what not.

I would try to explain that traditionally, nothing was worn underneath, but really it's to person and what they find most comfortable. If I was asked directly as to what I was wearing, depending on the situation I would probably say something like "Sock and shoes", "I prefer to go regimental," "That's a bit personal, isn't it?" with a smile. Honestly, I don't any reason to be rude unles the person is being rude to you first.