I've never been asked, but always intended to use the same line as Rex and tell them they'd have to ask me on a date to find out. I've never thought about what if a guy asked me, but I'd probably just look at him weird and ask if he really wanted to know in a tone that would hopefully stave him off. Though I might just tell him "Same thing as I would wear under pants."

The conclusion I've come to is that because the kilt is still so rarely seen by the public and they somewhat think of it as "costume", and since they have preconceptions about it (e.g. underwear not being worn under it and the wearer must know how to play the bagpipes) they simply can't help but to find out the truth to these age old curiosities. They think it's an innocent question to ask. I think this question won't go away until the kilt is seen more regularly by the public.