Kilts are often worn instead of a black tie and suit at formal occasions such as weddings. The kilt is a really flexible outfit and can be formal or informal and traditional or modern. The pattern of the kilt and the choice of jacket, shoes and socks can make a real fashion statement.
Met a Scotsman in Inverness, Scotland while traveling with friends. I asked him if it's true "what a Scotsman does or doesn't wear under his kilt". He said if I met him later, he'd show me. But I didn't!!!!