(CNN) -- Seeing more mustaches this month? Many of them may be fighting cancer.
On November 1, global health charity Movember kicked off its signature event, a monthlong campaign encouraging participants to grow mustaches (or "mo"s) to raise cancer-fighting awareness and funds.
According to Adam Garone, Movember's CEO and co-founder, there are already more than 700,000 registered participants this year, and he expects to break 1 million -- a record for the organization.
That's quite the growth for a project that started with 30 guys in Australia in 2003.
It was a social experiment back then, Garone said, with a simple goal: "It was really just for fun. We wanted to bring back the mustache."
But people quickly caught on, and it began generating a "surprising amount" of conversation, Garone said.
The following year, four of the original 30 got together and decided to do it all over again -- for a cause.
With a little research, they discovered that prostate cancer was a major health concern for men and decided it could benefit from an open, ongoing conversation.
Unlike breast cancer, which has been supported by major educational and fund-raising campaigns for years, prostate cancer hadn't been spotlighted in a substantial way.
"Growing a mustache is a very manly pursuit," Garone said, so the group chose prostate cancer as its primary cause, with men using their mustaches, and faces, as billboards.
That year, 450 guys participated, raising $43,000.
Last year, 855,203 people participated around the world, raising $126.3 million.
The organization's strategy is simple: Keep people talking -- about mustaches, and the larger issue of men's health.
Research last year showed that participants have, on average, 2,400 Movember-related conversations a month, Garone said. About 30 are face to face.
Social media causes that message to amplify, he said. Users have taken to Facebook pages and Twitter accounts to document their individual, ongoing facial hair activism.
It isn't just one person asking another, "Why the mustache?" The answer spreads to 100 -- or 1,000.
"The conversations do lead to a greater understanding," Garone said.
Movember encourages both men and women (nicknamed "Mo Sistas") to participate throughout the month by registering through Movember.com.
The website has evolved an elaborate internal slang, including terms such as "Mo Mentor" and "Gala Parté," which is what participants call their end-of-the-month celebrations, and it has information on everything from grooming tips to health risks.
The rules are simple: Don't start with any facial hair and end with a lot.
Garone's been asked before: Why a mustache, not a goatee or beard?
"It is a mustache,'" he said. "And it's a mustache for a reason."