To judge from the media, the presidential candidates have been spending half their time extenuating their own mistakes and the other half repudiating the things said and done by their supporters and friends. So it's not surprising the phrase "under the bus" has appeared in more than 400 press stories on the campaign over the last six months. Under the bus is where Hillary was described as throwing her chief strategist Mark Penn, and where the radio talk show host Bill Cunningham said John McCain had thrown him after McCain disavowed Cunningham's reference to "Barack Hussein Obama" at a McCain rally. And after Barack Obama's speech on race, under the bus is where he was accused of throwing his grandmother by Ann Coulter, Fred Barnes, Rich L0wry and Karl Rove, not to mention well over a hundred other conservative columnists and bloggers. That piling on might suggest a certain lack of originality. But it takes a lot of self-restraint to pass up an opportunity to charge a politician you don't like with throwing his grandmother under a bus, even if it's only in a manner of speaking.

That helps to explain why "throw someone under the bus" has shot so quickly from new kid on the block to the idiom A-list. The word sleuth Grant Barrett has traced it back as early as 1991, but its origins are lost in the mists of the 1980's.

Some people suggest it's derived from a phrase for a washed-up rock star on tour, and others connect it to the announcement made by a minor-league baseball manager: "Bus leaving. Be on it or under it." There's no evidence for either origin. But we always assume that there has to be some real-life scenario behind each of these metaphors, however far-fetched it is, and the internet and bookstore shelves are teeming with treasure-troves of word lore eager to oblige us with ingenious speculations. As in, See, back in Elizabethan times the household pets used to curl up in the thatched roofs to keep warm until they were washed out by a downpour.   

You hear a lot of talk these days about the wisdom of crowds, but when it comes to the crunch, we're reluctant to credit the collective mind with the same creative imagination that we accord to an individual artist. It's as if we expected Bob Dylan to be able to point to the event that inspired every line in his songs: "So then I wet my finger and stuck it in the air and I said…"

Actually, it's my guess that somebody just pulled "throw under the bus" out of the ether one day, and other people picked it up and passed it along. It's what marketers like to describe as a viral process, except that these aren't exactly like the mysterious fads that can instantaneously populate every kindergarten class with Ethans and Emmas. The geography of betrayal is already mapped out pretty thoroughly in English: you can hang someone out to dry, throw him to the wolves, let him twist in the wind, sell him down the river, offer him up as a scapegoat, or make him a fall guy, a patsy, or a sacrificial lamb. So "throw under the bus" couldn't have caught on unless it suggested a compelling new take on familiar perfidies.

Or probably I should say new takes, since the expression seems to conjure up different things for different people. Some think of the thrower and throwee as fellow passengers on a team bus or tour bus. That would explain why we talk about the bus rather than a bus, and it foregrounds the idea of a betrayal. But it makes the action a little hard to picture, since you have to imagine one rider on a moving bus managing to throw another rider under its wheels, which seems like a stunt from a Steven Seagal movie. So evidently a lot of people just picture the victim being pushed off a curb in front of an oncoming Greyhound.[1] But one way or the other, the expression conveys a singularly modern image of stop-at-nothing ruthlessness.

These things work like little film clips. You hear "He made her take the fall," you flash on The Maltese Falcon; you hear "He threw her under the bus" you envision some more recent movie -- I don't know exactly how the plot goes, but it probably features Javier Bardem.

We have more exacting standards in mayhem these days, whether in our movies or our metaphors. There was a time when the emblemmatic moment of movie sadism was Jimmy Cagney shoving a half-grapefruit into Mae Clarke's face in The Public Enemy, and when people could still get a vicarious tingle out of saying that so-and-so got worked over or got the living daylights beat out of him.

But those expressions seem pretty demure for the age of Hannibal Lecter and Anton Chigurh's pneumatic cattle gun. The verbal violence that we get off on is a little more graphic, which is why Google reports nearly a quarter of a million hits for tearing somebody a new one.

I have some trouble imagining Cagney using that phrase, probably for the same reason it's hard to picture Sam Spade telling Bridget O'Shaughnessy "Angel, I'm throwing you under the bus." That's not a judgment, mind you. But every age seems to get the idioms it needs.

1. These may be the same people who use the expression more loosely to refer only to blowing the whistle on someone or trashing someone's reputation, without necessarily implying a betrayal of loyalty:

Witness the uproar after Mr. Obama’s remarks about “bitter” voters finding succor in God, guns and great big fences. Mr. Obama was speaking at a small fund-raiser in San Francisco to a group of supporters in an event everyone assumed was off the record. Well, not everybody. As it turned out, the media member who threw Mr. Obama under the bus was never really on it. (David Carr, New York Times, 4/21/08)