This month, you may notice the bare upper lips of some of your male colleagues slowly growing fuzzy. If you’re wondering why they decided to go all Burt Reynolds, here’s the scoop: Your coworkers have jumped on the “Movember” bandwagon.

Movember is a global men’s health charity that encourages men to grow and women to support the “Mo,” or moustache, for the 30 days of November. Over 3 million “Mo Bros and Mo Sistas” have raised more than $446 million since the program launched in 2004 in Melbourne, Australia.

In just its tenth year, the group will host official Movember campaigns [PDF] in 21 countries. U.K.-based Third Sector Research named Movember the most talked about charity of 2013 in its annual Charity Brand Index.

Movember initially began as a joke among a group of 30 friends that were looking to “bring back a past fashion trend,” according to the group’s website, but once they realized how fast the trend was spreading, a handful of them decided to attach the event to a charitable cause—prostate cancer awareness.

“One of the biggest obstacles men tackle in regards to general well-being is a reluctance to discuss health issues they face either with their partner, family, or doctor,” the website states. “Movember was born from recognition that a fun and engaging initiative could help encourage men to become more actively involved in their own health. Movember aims to increase awareness and support for men’s health by getting conversations started at a grassroots level, educating men about the health risks they face, and raising vital funds for support programs.”

That mission has attracted support from other prominent organizations, including the Prostate Cancer Foundation (PCF) and the Livestrong Foundation in the U.S. Funds raised during November are split by the organizations and go toward funding prostate and testicular cancer research.

“We are proud to partner with Movember to fund these cross-disciplinary teams of scientists with bold approaches to the most challenging and perplexing problems in prostate cancer research,” Jonathan W. Simons, president and CEO of PCF, said in a recent statement. “We are profoundly grateful for the generous support of the Movember community.”

Movember isn’t the only effort putting the mustache to work in support of good causes. On a smaller scale last month, the American Mustache Institute’s ’Stache Bash, which recognized the Mustached American of the Year, benefited a Pittsburgh-area charity providing education programs to children with disabilities.

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