I would add to what has already been said about offense taken concerning "demeaning" Scots and Scotland by calling the kilt a skirt and say that if you have anyone in the crowd who is sensitive about gender, gender roles, etc, your "masculine" comment might be just as offensive to them as anything else. Kilts = skirts, skirts = women, men > women. Lots of unfortunate, unconscious assumptions going on there. It's something that touches a nerve in me every time I hear it, even. Perhaps it would be best to practice a lighter touch with the humor?