The cliché: When Obama debuted his $1.1 million bus, people tried out a lot of different nicknames from "Greyhound One" to "the 'Matrix' bus". The Washington Post's Kathleen Parker says it looks like "a land shark from Mordor" or "a creation out of Batman and the president appears as Paul Revere of the Apocalypse." But among the metaphors, one name displayed uncanny "force": The Darth Vader Bus.

Where it's from: Almost the moment the presidential bus rolled onto news shows and computer screens, people started jokingly making the comparison between the black armored bus and the Star Wars villain. It seems a bunch of people quickly and probably independently drew the comparison, but chief among them was Paul Brandus of the West Wing Report (@WestWingReport) who tweeted "The President's tour bus would do Darth Vader proud. All-black. Dark-tinted windows. No markings whatsoever. No doubt heavily armored." He tweeted it almost immediately after the bus's debut Monday, and given his 62,000 followers, it seems likely he should take a lot of credit for getting the Darth Vader ball rolling. Fox News and Gawker soon gave it big play in their stories on the bus. In the days since, it has become common parlance. Rep. Louis Gohmert went on TV to say the president was riding "his Darth Vader bus" on a "magical misery tour."  Today, Kathleen Parker wrote in her Washington Post column that the bus "couldn’t be less effective — unless you’re Darth Vader."

Why it's catching on: Well, beyond the fact that Obama's bus is black, hulking, and made of machine, like our friend Darth, pundits are using it more broadly to cast Obama as a villain. There's a lot his opponents don't like about this bus. It cost tax-payers $1.1 million, it was made in Canada, and tax payers are footing the bill despite its resemblance to a campaign bus. Even Obama-friendly pundits like Parker are using the term, although that's mostly just to point out that others are criticizing it.

Why else? This seems like a game of partisan payback. Darth Vader, with his daunting John Williams theme music and penchant for choking people with his mind, has long been a metaphor thrown around in politics -- but usually it's Democrats doing the name-calling. Pretty much everyone took to calling Vice President Dick Cheney Darth Vader. But Maureen Dowd said it was George W. Bush who should be cast as Darth Vader, with the more supreme Emperor Palpatine played by the vice president. So, suffice it to say, as soon as a Democratic president rolled out of his garage in vaguely Vader-like outfit, Republicans were given the chance they'd been waiting for through eight long years of Dowd columns. And they have certainly taken it.