I was in the local Carrefour one day and I noticed a man, maybe 50 or 60 years old, walking through the store in his pajamas. Long-sleeved, button down, striped pajamas. My judgmental voice went off in my head thinking "These crazy Chinese people - walking around in his pajamas." I later learned this is not crazy at all. It is, in fact, a long tradition. I researched some of the hypotheses as to the origin of this tradition. Here are some of the tidbits I discovered:
Daytime public pajama wearing has its roots in the Chinese shikumen housing practices. Shikumen housing is communal living where families have sleeping rooms but share kitchens, bathrooms and toilets so it was common to see others in their pjs.
Women, who spent the bulk of their time in the home, needed a break from their cramped quarters so they would extend their 'home' to the stores and streets surrounding their home and would commonly go to shop in their, more comfortable, pajamas.
In the 1930's wearing pajamas during the day was in vogue in Shanghai. They were not considered sleepwear but rather casual wear for after work. They were (and still are) seen as a sign of affluence. Since people generally do not go far from home in their pj's (see above paragraph) then wearing pj's in downtown Shanghai - particularly the affluent areas like Nanjing Lu - makes the statement "I am an authentic Shanghainese!"
Furthermore, wearing pj's during the day says "I am so wealthy, I don't need to go to work today." (In Michigan wouldn't this say 'I am unemployed and depressed.'???)
So not only is it acceptable to wear pj's in Shanghai, it is fashionable! Until now. Apparently the face-saving Chinese do not think the international community will look favorably upon its citizens wearing their pj's in public during the upcoming 2010 World Expo. So they are cracking down - peer pressure style. They (the infamous 'they' here in China) have enlisted the aid of teens and young adults to mock the pj wearing folks into embarrassment, a state which is unacceptable to Chinese people. There is even a slogan for this movement:
"Do not go outdoors in pajamas, be a civilized person for the Expo." Too bad in their desire to show us who they are, they feel they have to hide some of who they are.