To "Die with your boots on" is an idiom referring to dying while fighting or to die while actively occupied/employed/working or in the middle of some action. A person who dies with their boots on keeps working to the end, as in "He’ll never quit—he’ll die with his boots on." The implication here is that they died in violence, as in gunfights or by hanging and didn’t die of old age and/or experience of being bedridden with illness, infirmity, etc.

Origin

The "Die with your boots on" idiom originates from frontier towns in the 19th century American West. Some sources (e.g. American Heritage Dictionary of Idioms) say that the phrase probably originally alluded to soldiers who died on active duty. The Oxford Dictionary of Idioms says: “Die with your boots on was apparently first used in the late 19th century of deaths of cowboys and others in the American West who were killed in gun battles or hanged.” Cassell’s Dictionary of Slang adds that from the late 17th century until the early 19th century the expression meant ‘to be hanged,’ and from the mid 17th century until the mid 19th century Die in one's shoes meant the same thing.

In Popular Culture

• "Die with your boots on" from Iron Maiden
  Iron Maiden
  Iron Maiden are an English heavy metal band from Leyton in east London, formed in 1975 by bassist and primary songwriter Steve Harris. Since their inception, the band's discography has grown to include a total of thirty-six albums: fifteen studio albums; eleven live albums; four EPs; and six...
  
  's 1983 album Piece of Mind
  Piece of Mind
  Piece of Mind is the fourth studio album by British heavy metal band Iron Maiden. It was originally released in 1983 on EMI, and on Capitol in the US; it was reissued later on Sanctuary/Columbia Records...
  
  
• "Die with your boots on", a song by Toby Keith
  Toby Keith
  Toby Keith Covel , best known as Toby Keith, is an American country music singer-songwriter, record producer and actor. Keith released his first four studio albums — 1993's Toby Keith, 1994's Boomtown, 1996's Blue Moon and 1997's Dream Walkin, plus a Greatest Hits package for various divisions of...