Onesie is basically a casually fitted jumpsuit for kids and adults which are very comfortable and is meant to worn to bed. The onesies have been in the market since 2000 but in the last couple of years, it has become a fashion statement for a lot of people. A few years back onesies were considered as a fashion disaster but recently most of the Hollywood celebrities have been rocking the onesie look on the streets. Justin Biber is one of the popular celebrities who like to wear onesies out in public.