Scary sightings are usually preserved for the last day of October, yet in London's Square Mile -- and across the world -- an even more chilling sight will greet people at the end of November: a sea of men in unkempt mustaches.
For nearly a decade, "Movember" has seen men grow a mustache for 30 days to raise awareness and money for men's health, namely prostate cancer, testicular cancer and men's mental health.
In 2004, in its first fundraising year in Australia, 450 participants raised 43,000 Australian dollars ($40,900). In 2012, 21 countries participated, with 1.1 million people raising £92 million ($147.5 million).
It has been a phenomenal rise for a fundraising model that initially started as a joke among friends in Melbourne in 2003.
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"They were in a bar and kind of musing on what was currently in fashion when they were served by a girl wearing a Ramones t-shirt, tight jeans and Vans," Jon Sim, the corporate community manager at Movember told CNBC. "They said, 'How come everyone's wearing that now? We've been wearing it for years!' So they started to muse on what would never come back into fashion, started laughing about cricketing heroes with mustaches, and dared each other to grow one."
It was only when they later saw how many men were dying from prostate cancer that they decided for the following year they would grow their mustaches for charity.
According to World Health Organization (WHO) statistics, prostate cancer is the sixth most common cause of cancer death in men worldwide and was estimated to be responsible for almost 258,000 deaths in 2008. In the U.K. in 2010, 10,700 men died from prostate cancer, roughly 29 every day, according to Cancer Research U.K.
Movember's connection between the male-only art of growing a tache and men's health charities has been successful in putting the fun into fundraising, especially when men would rather not run a marathon to raise money for a good cause.
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"Absolutely," Sim said. "It's a lazy man's charity: get online, grow your "mo" and have some fun with your mates."
People in The City of London, the heart of the U.K's financial services sector, have been particularly enamoured with the event, no doubt pleased to raise money without having to take time away from their desks.
Movember's official birth year, 2004, was also the year in which Facebook first came online, and Sim argues that this has been crucial to expanding awareness.
"I think it's grown in parallel with social media," he said. "I might be wrong with the phraseology when talking about charity, but I think there has been a gap in the market for a men's health charity to tap into men's health in the same way that the Pink Ribbon movement did for female cancer."
Corporates and celebrities
Celebrities and companies have jumped on the Movember bandwagon. Byron Burger, an upmarket hamburger chain in the U.K., produces a different burger every November to support the cause and contributed over £120,000 ($192,000). TOMS shoes and Gilette are also Movember partners.
The Formula 1 driver Mark Webber and an assortment of U.S. football players are set to take part this year, with Homeland actor Damian Lewis being one of a number of celebrities to take part in former years.
This year in the U.S., Nick Offerman, who plays Ron Swanson in NBC's Parks and Recreation, has teamed up once more with Movember to produce a video for the campaign, "Great Moments in Mustache History." In 2011, 209,342 people participated in Movember in the U.S., raising nearly $21 million.
Some have been critical of the growth of Movember, arguing that either growing a mustache is far too lazy a way of raising money for charity, or that the spectacle has meant most men participate just for the fun, without any awareness of the charities involved.
"It's a way of engaging blokes; it's a way of creating some fun," Sim responded, arguing that Movember has provided key sums to cancer research. "We're currently funding ground-breaking research into prostate cancer and doing more practical projects with Prostate U.K. and Cancer U.K., anything from community hubs where people can get psycho-sexual counselling to employing dedicated prostate cancer nurses."
(Read more: Rich, forget charity, start businesses: McNealy
Some people definitely do fall into Movember without an awareness of what it is about, but that can quickly change.
Nick Dart, who works at Deutsche Bank, told CNBC that he had grown a mustache last year just for a bit of fun and did not raise any money. "Now, I'm taking it seriously because it's a really important cause, and I think it's quite fun to take it really seriously and go head-strong into it," he said.
Dart's colleague, Richard Fox, concurred. "A couple of guys in my team are doing it this year so they kind of roped me in," he said. "Originally we started out doing it as a bit of fun, and then we read into and realized it's raising money for a good cause."
This year, a large number of financial firms will once again get involved in Movember. Last year, roughly £300,000 ($481,000) was raised through the Square Mile financial challenge that pitted firms against one another in a race to raise the most cash. Accountancy and law firms have also enthusiastically been involved with Movember. So what's the allure?
"I think particularly in the City, people like a dress-down Friday, and this is just almost like a dress-up month where people can let loose a little bit" Sim proffered. "I think it taps into a bit of an innate eccentricity in Brits, particularly in guys who are dressed up in suits in the City. It's a chance to cut loose a little bit."