London, England (CNN) -- At least half a million Facebookers are raging against Simon Cowell, trying to keep his British TV talent show "The X-Factor" from claiming the number-one spot on the British singles chart on Christmas Day.
They've vowed to download the Rage Against the Machine song "Killing in the Name" starting Dec. 13 to make it the number-one single in the country on the Sunday before Christmas.
It might seem like a frivolous contest, but hundreds of thousands of pounds -- and a place in history -- are at stake.
A Christmas Number One enters the history books, exciting passion, disgust, joy and, yes, rage.
British music fans sometimes take the high road. They put the charity single "Do They Know It's Christmas?" at the top of the charts three times: First in 1984, then in 1989 and 2004 when anniversary editions came out.
Once upon a time, they got into the spirit of the season -- with "Rudolf the Red-Nosed Reindeer," "Mary's Boy Child," and "When a Child is Born" all topping the charts on Christmas Day in days of yore.
And often they just buy the songs they like, paying no heed to the season's mistletoe and wine. The Beatles topped the Christmas Day chart four times. The Spice Girls claimed the title three times. Whitney Houston, Michael Jackson, Elvis Presley and Westlife all had Christmas number ones.
So did Pink Floyd, with "Another Brick in the Wall." (Merry Christmas, everyone!)
Most infamous of all are the songs that drive you around the bend.
Mr. Blobby's single "Mr. Blobby" -- no, really -- was the 1993 chart-topper.
The theme song from the kids' show "Bob the Builder" took top honors in 2000. Slapstick comic Benny Hill ruled the charts in 1971 with "Ernie (The Fastest Milkman in the West.)"
And, to the everlasting fury and despair of John Lennon fans, "There's No One Quite Like Grandma," by the St. Winifred's School Choir, claimed the top spot in 1980, weeks after the former Beatle was gunned down, knocking off his "(Just Like) Starting Over."
Historically, there has been a lively business trying make Christmas number ones -- and to predict what they will be, said Rupert Adams of the William Hill betting shop.
"It used to be massive -- five years ago you would have all the big record producers try to get in on the Christmas sales," he said. "Hundreds of thousands of pounds" would be wagered on the results, he added.
Then came Simon Cowell, the flat-topped, smirking, eye-rolling impresario behind "The X-Factor."
Winners of his talent show have taken the top slot for the past four years, and William Hill now runs a separate pool for betting on what will be the number two single -- behind "X-Factor winner," as they generically call it.
Cowell is the unstoppable force in front of which Jon and Tracy Morter are trying to put an immovable object.
"2009 X-Factor is in its final stages and we need to gain more people here to try once again to stop this manufactured crap stealing our national heritage of a CHRISTMAS No.1!!" they say on the page of their Facebook group.
"We were bored of the Christmas Number One being predictable," Tracy Morter said. "When we grew up it was always exciting wondering what it was going to be. (The song) was sometimes rubbish but it was fair."
Now, she said, people are pre-ordering the X-Factor winner's song without even knowing what it is.
They've signed up more than half a million members in a week for a Facebook group dedicated to putting Rage Against the Machine on top of the charts.
Rupert Adams, for one, is taking notice.
"X-Factor winner" still tops his list of most likely chart-toppers -- people who place a £5 bet on it at William Hill will win only £1 if they're right -- but the Morters are at least making it competitive.
Adams -- who runs the William Hill betting, or "book" on the Christmas Number One -- makes Rage Against the Machine the second most likely winner. William Hill will pay out £10 on a £3 bet if "Killing in the Name" takes top honors.
"X-Factor will sell somewhere around 800,000," guaranteed, Adams said. "For Rage Against the Machine, on Monday I would have given you 100 to 1. But since then, there's this Facebook group and they now have half a million members."
The critical question -- and what makes this fun for Adams, he said -- is whether group members will actually shell out money on the song.
"We have absolutely no idea how strong this group is," he said. "Having lots of mates on Facebook doesn't mean you are going to transfer that to sales."
Cowell himself dismissed the campaign as "stupid.
"It's not going to change my life particularly" if the X-Factor winner isn't number one on Christmas, he said at a press conference with the show finalists in London Thursday. "It does, however, change these guys' lives."
Cowell accused the Facebook group of "treating our audience as if they're stupid," and said the Rage Against the Machine movement was "quite a cynical campaign geared at me."
Tracy Morter laughed off the accusation.
"He's going to get his sales anyway -- we're not going to persuade people not to buy it," she said. "People are pre-ordering without even knowing who won."
What she hopes is that people who would not normally buy music will purchase the Rage Against the Machine single -- and donate money to Shelter, a homeless charity, at the same time.
She insisted she did not have a grudge against X-Factor contestants.
"We're not against the contestants in any way. I watch it. I enjoy seeing who's good and who's not," she said.
Cowell proteges are unlikely to spend Christmas unwrapping presents alone, whatever happens.
Before the final chart week, William Hill listed Susan Boyle as the fourth most likely Christmas chart-topper, at 25-to-1 (behind Walt Disney-backed Miley Cyrus at 20-to-1), and former "X-Factor" winner Leona Lewis as sixth, at 33-to-1.
Just as a reminder of how random the Christmas Number One contenders can be, the Muppets are joint fourth with Boyle, the frumpy Scottish woman who went viral when she sang "I Dreamed a Dream" on Cowell's show earlier this year.
Lady Gaga, Michael Jackson, Take That and George Michael round out the top 10, while number 11 is World War II sweetheart Vera Lynn, whose greatest hits album this year fueled a mini-comeback this year for her -- at age 92.
Whatever the winner, oddsmaker Adams is delighted that the field is once again competitive.
"It could be a bumper year" for betting, he said. "It could be the best year since the X-Factor came onto the scene."
Then again, it might -- just might -- be another year like 1972, when Little Jimmy Osmond topped the charts with "Long Haired Lover From Liverpool."