Long long ago I was a very bad highland dancer. The Scottish Official Board of Highland Dancing decreed that we should wear black briefs beneath our kilts when dancing. A friend went into one of the better department stores and asked for a pair. The clerk said, "Does your MOTHER know you're buying those?" So much for the SOBHD.

I knew a kid in a pipe band, who wore a very elaborate uniform. When we kidded him about it, he kidded back telling everyone that he had $500 worth of plaid underwear under it. Now, when you are 15 that is a challenge. So three of us bought a pair of plaid boxer shorts and sent them to him for his birthday. Mother spent years avoiding his mother, because they fit, and the good lady would never believe we had guessed his size.

At an SCA event, one of the Scots was quite drunk. Some female asked him what he had under his kilt, he whooped and pulled it up to show her. She reacted like she'd never seen one before. (And I know for a fact she'd seen several.) Screamed and hid her face.
He was so pleased with the reaction that he showed Justinian, our resident fop.
Justinian eyed the display, clucked his tongue and said, "Is that all?"