Today, men all around the world participating in Movember can shave their moustaches in solidarity.
Men participating in "Movember" grew moustaches -- or "mo's" in Australia -- for the entire month of November to raise money and awareness for men's health, specifically prostate and testicular cancer.
The unique charity was founded in 2003 in Australia. Aussie Adam Garone was joking with his friends one day that they should bring back the moustache as a fashion icon. They decided they would grow moustaches for the month of November, and rename November "Movember."
"We all got so much grief that year that I said to the guys, 'We need to legitimize this so we can get away with it,'" Garone said.
Garone said that since some of his friends' fathers were affected by prostate cancer, they decided to dedicate their month-long moustaches to cancers affecting men.
"We thought, let's use the moustache as our hairy ribbon to raise awareness and funds for prostate cancer," Garone said in an interview with ABC News.
Garone said men participating in Movember are likely to pre-empt people's "weird looks" by explaining they were participating in an awareness and fundraiser for cancer prevention.
"The moustache opens up all these amazing conversations about our health and cancers that affect us," Garone said.
Garone brought Movember to the U.S. in 2006, where it's catching on with some younger American men.
New York native Michael Mattis, 34, is a first-time participant in Movember. He took part because a friend got him into it.
"I found out about it through a friend, and as I read up on it, I thought it would be a worthy cause to lend your time to -- and my facial hair and moustache," Mattis said.
He also said his father had dealt with prostate issues, and that also made him want to join the cause.
"As a man, I have to worry about stuff like this down the line, and if there's ways prostate and testicular cancer can be prevented, I'm all for it," he said. He and his five other team members raised $605.
With the help of online social media -- Facebook, Twitter, YouTube and Flickr, Movember has become a worldwide event.
This year, it will raise over $47 million, becoming the top fundraiser for men's prostate and testicular cancer worldwide, Garone says.
Movember has even caught the attention of cancer survivor Lance Armstrong.
Garone said Armstrong contacted the Movember Foundation when he was on a bike tour in Australia. Armstrong himself participated in Movember this year, even tweeting a picture of himself with a sparsely-grown moustache to the Movember Facebook page. Funds raised in the U.S. from Movember will go to Armstrong's foundation, and the Prostate Cancer Foundation.
Janet L. Stanford, Ph.D. from the Fred Hutchinson Cancer Research Center said one in six American men will be diagnosed with prostate cancer over a lifetime.
"Prostate cancer is the most frequently diagnosed cancer, excluding melanoma, for men. It accounts for a quarter of all new cancer diagnoses in men. It's projected this year, over 192,000 will face this diagnoses," Stanford said.
"Raising awareness is important because prostate cancer generally doesn't cause symptoms. So most of the cases detected are detected on the basis of a positive psa blood test," Stanford said.
She said men with a first-degree relative with prostate cancer and African American men starting around age 40-45 should begin psa testing. Men in the general population, she said, should begin testing around age 50.
Stanford said testicular cancer was rarer than prostate cancer. However, testicular cancer is the most common cancer affecting men ages 18 to 35.
"Men in particular, don't like to talk about our health, and we certainly don't like to talk about cancers that affect us," Garone said.
But he said, so far, it's been a lot of fun.
"I think the majority of us want to know what we look like with a moustache," he laughed.
Garone said that according to the "official Movember styleguide", his moustache is called "the undercover brother."
"It was fun trying to grow one because normally I don't keep a thick moustache, but it was fun trying to grow a moustache and compete with my friend and everyone on the team," Mattis said.
Does he plan to shave his today?
"I've kind of grown attached to it," he said. "It keeps my face warm in the winter."
Another good excuse to grow a mo.