ADDED: The linked article prompted me to research the history of the term "to go commando." The Oxford English Dictionary traces it to 1974:
slang (orig. U.S.). to go commando : to wear no underpants (beneath one's clothing).
The origin of this use is obscure; the allusion appears to be to commandos' reputation for action, toughness, or resourcefulness rather than to any specific practice.1974 Current U.N.C. Slang (Univ. N. Carolina, Chapel Hill) (typescript) Spring, Go commando, to be without underwear.
1985 Chicago Tribune (Nexis) 22 Jan. c, Colored briefs are ‘sleazy’ and going without underwear (‘going commando’, as they say on campus) is simply gross.
2001 Guardian 7 June ii. 8/2 Thank goodness he wasn't wearing a pair of sagging Y-fronts or, much worse, a thong. Thank goodness he wasn't going commando.
2004 J. Evanovich Ten Big Ones 186 Unless Ranger kept his underwear in his safe, it appeared that he went commando.