Shanghai Bans Wearing Pajamas in Public City wants to curb trend before hosting World Expo By John Johnson, Newser Staff Posted Feb 5, 2010 2:04 PM CST 19 comments Comments Shanghai officials want their residents to keep their pajamas to themselves. (Shutter Stock) (Newser) – Shanghai wants to look its best when it hosts the 2010 World Expo in a few months, so it's spreading the word to residents: Pajamas are for inside the house. Concerned about the popular habit of wearing boldly colored PJs on city streets, officials have launched a public campaign to discourage the practice. Boing Boing notes that the trend has been immortalized on Flickr and in National Geographic. The fashion statement began "as a matter of practicality because people lived in cramped conditions with no clear line between public space and private place," a Chinese sociologist tells the South China Morning Post.