Pajamas
I stumbled upon this article about a college student who wears pajamas to class most days, and thought of two things.

1.) During my high school years, I attended a boarding school in Conneticut, and we had a dress code for all class days and meals. Mostly, the administration hammered this out but not allowing blue jeans in class. We were allowed to wear any other color jean (as was the style at the time), but nothing too casual. Basically, we were a walking student body of "business casual." Anyway, the rules did NOT specifically disallow pajamas, so many students, including myself, would wear pajamas to class in the mornings. These were not light cotton jobbies that might be taken for palazzo pants: these were the real-deal-LLbean-red-flannel-plaid pajama pants that you might match with the always dependable J.Crew rollneck sweater (it was a prep school, after all). I would probably wear my pajama pants at least a couple days out of five. So many people wore them that I didn't think anything of it. I bet it drove the administration crazy.

2.) When we visited Shanghai, back in my time in China, it was the fashion for people to traipse around during the day in their light cotton pajamas. People would wear them lounging in tea shops, standing outside chatting with friends, or while they ran errands during the day. I think it may have been more among the older set, as my impression is that the younger-Shanghaiese are pretty fashion forward. I love the light-cotton pj style, though, because you really can't come up with a better outfit to wear in sweltering humidity. Yay for practicality!