A union suit is a type of one-piece long underwear. Created in Utica, New York, United States, it originated as women's wear during the 19th-century United States clothing reform efforts, as an alternative to constricting garments, and soon gained popularity among men as well. The first union suit was patented in 1868 as "emancipation union under flannel". Traditionally made of red flannel with long arms and long legs, it buttoned up the front and had a button-up flap in the rear covering the buttocks (colloquially known as the "access hatch", "drop seat", "fireman's flap", and other names), allowing the wearer to eliminate bodily waste without removing the garment. Depending on the size, some union suits can have a dozen buttons on the front to be fastened through buttonholes from the neck down to the groin area.

The garment remained in common use in North America into the 20th century. As its popularity waned, it became chiefly working men's wear, increasingly replaced by two-piece long underwear, also known as "long johns". It was not uncommon until the mid-20th century for rural men to wear the same union suit continuously all week, or even all winter.^{[citation needed]} Normally, no other type of underwear was worn with it.^{[citation needed]}

William Toliver Carlisle (December 19, 1908–March 17, 2003) was an American country music singer, songwriter, comedian and guitarist popular in the late 1940s and 1950s but who influenced the genre for more than 50 years. He is a member of the Country Music Hall of Fame.

Bill Carlisle was born in Wakefield, Kentucky southeast of Louisville. He performed in the 1920s with his older brother, Cliff Carlisle, on radio stations WLAP-AM in Lexington, Kentucky and WNOX-AM in Knoxville, Tennessee. His first solo single and hit was the 1933 recording of "Rattlesnake Daddy," released on ARC Records. That year he formed the Carlisle Brothers with Cliff, and in 1938 they signed with Decca Records and continued performing on Kentucky country radio programs. He created an alter ego for the WNOX's Mid-Day Merry-Go-Round and Tennessee Barn Dance shows called Hot Shot Elmer, a bumbling buffoon in costume who would "interrupt" Carlisle's own performances. His leaps on stage won him the moniker "Jumpin' Bill."