Unless you've been living in a spider hole, it will neither shock nor awe you to learn that military slang has become increasingly, uh, embedded in American popular culture.
While hardly a new phenomenon - the military has been a source of American slang since the Revolutionary War - it does seem to be having a growth spurt. Ever since the World Trade Center was designated "ground zero," it has been (damn the torpedoes) full speed ahead for military jargon.
Not all of it reaches catch- phrase status. Some phrases, like old soldiers, simply fade away. Such, thankfully, was the case with Secretary of Defense Donald H.Rumsfeld's "known unknowns." Others hang on to become part of our everyday vernacular.
Time will tell which will be the case for the latest military metaphor to hit the airwaves - one that has been bandied about by no fewer than four of the participants in this week's 9/11 hearings:
"Hair on fire."
That odd phrase - believed to have originated among Navy aviators, intended to convey a sense of hair-raising urgency - quickly became the phrase of the day as this week's hearings began before the commission investigating events that led to 9/11.
First, it came from Richard Ben-Veniste, a commission member recounting allegations that President Bush ignored al-Qaida before the attacks, despite warnings from alarmed officials:
"People like [CIA] Director [George] Tenet, people like [former counter-terrorism chief] Richard Clarke, are running around, as they say, with their hair on fire, in the summer of 2001, knowing something big is going to happen," he said.
Then Rumsfeld used it, saying such alarm wasn't uncommon: " ... In the three years since I've been back in the Pentagon, there have been people running around with their hair on fire a lot of times. It isn't like it's once or twice or thrice."
Still later, Jamie S. Gorelick, another commission member, seized the metaphor: "If you look at the headlines ... in the period that has come to be known as the summer of threat, it would set your hair on fire, not just George Tenet's hair on fire."
Clarke, the Bush critic who appeared before the commission Wednesday, uses the phrase at least twice in his new book, Against All Enemies, Chapter 3 of which begins: "Charlie Allen had his hair on fire."
The repeated allusions to burning coifs were enough to make one wonder - amid the far more important questions the hearings are raising - just where that phrase came from.
Capt. Earle Rogers, a retired Navy flier who is vice president for communications at the Naval Air Museum Foundation in Pensacola, Fla., says the phrase goes back at least 25 years, probably more.
"I think the term is probably specific to naval aviation," he said. "It's just a phrase somebody coined, I'm not sure when. But it's one we all understand."
But what does it mean?
Too much going on
"Just what it sounds like," Rogers said. "You use it to describe one of those days that are just so frustrating, where you have so many balls up in the air, and you're trying to juggle so many things."
Like, that, but more under control. "It's like when you're going around in tight, tight circles ... trying to keep out of the way of enemy fire. Your hair can be on fire, but you still land the plane safely."
Rogers said that, to his knowledge, the phrase has nothing to do with the hair of pilots actually catching on fire in flight - it's more a figure of speech. He said he wasn't surprised to hear it was used by Rumsfeld, whose father was a Navy aviator.
As with most slang, its precise origin is difficult to pinpoint, and interpretations of it vary. Some use it to describe chaos, some use it to describe alarm, some use it to describe the edgy thrill of being a fighter pilot.
"This is the problem with slang," said John Reilly, an historian at the Naval Historical Foundation in Washington. "It's casual, it's informal. It's not like a memo goes out: From chief of naval operations to all hands, henceforth this will be called `hair on fire.'
"There are all kinds of words and phrases that have naval origins, or are related to the military, or weaponry - `half-cocked,' `lock, stock and barrel.' In the Civil War, if you'd been in combat, you'd `seen the elephant,'" he said.
While Navy aviators may have brought the phrase into more common use, references to "hair on fire" can be found much earlier - from the teachings of ancient Buddhists to the 1939 James Joyce novel Finnegan's Wake.
Joyce was clearly - to borrow some more aviator jargon - pushing the envelope when he wrote: "The Flash that Flies from Vuggy's Eyes has Set Me Hair On Fire, His is the House that Malt Made, Divine Views from Back to the Front, Abe to Sare Stood Icyk."
Ancient Buddhist wisdom - a little easier to grasp than Joyce, or, for that matter, Rumsfeld - holds that a person should seek enlightenment in the same way a person whose "hair is on fire" would seek water, meaning with the utmost urgency.