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.
(Read more: America's most mustache-friendly cities)
"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.
(Read more: Why the wealthy don't give more to charity)
"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."