Long john Long underwear, also called long johns, or thermal underwear, is a style of two-piece underwear with long legs and long sleeves that is normally worn during cold weather. It offers an advantage over the one-piece union suit in that the wearer can choose to wear either the top, bottom or both parts depending on the weather. Long underwear is also less commonly known as long handles. It is commonly worn by people in cold countries. http://en.wikipedia.org/wiki/Long_underwear