Going commando is the practice of not wearing underwear under one's outer clothing. The term is theorized to be related to the much earlier term "going regimental", which refers to wearing the kilt military style, that is, without underwear. (See True Scotsman.)
In Chile, the act of not wearing underwear has been called "andar a lo gringo" (to go gringo-style) for decades.[1][2]
In Portugal, the expression used is "andar à caçador" (to go hunter-style).[3][4]
The origins of the phrase are uncertain, with some speculating that it may refer to being "out in the open" or "ready for action". Slate magazine's Daniel Engber dates the modern usage to college campuses circa 1974, where it was perhaps associated with soldiers in the Vietnam War, who were reputed to go without underwear to "increase ventilation and reduce moisture."[5] The earliest known use of the term in print occurred on January 22, 1985 when Jim Spencer wrote in the Chicago Tribune "Furthermore, colored briefs are 'sleazy' and going without underwear ("going commando", as they say on campus) is simply gross." Seinfeld's sixth season episode "The Chinese Woman" was thought to have originated the term in 1994, but this was in error. A 1996 episode of the television sitcom Friends, "The One Where No One's Ready", has been credited with introducing the term "into the popular vernacular".[6]