Ah, November, the month of the month-long challenges. Of course there are the writing challenges, like NaNoWriMo and NaPlWriMo. But there are also the hair-growing challenges: Movember and No Shave November, both of which involve growing hair for a month.

While NaNoWriMo and company are clearly challenges meant for everyone, the other two have collided directly with gender stereotypes, feminism, and male privilege. As No Shave November kicks off, many women are rushing to participate—in defiance of an onslaught of hostility from participants on Twitter.

Apparently, some women didn’t get the memo that No Shave Movember is a men-only pastime. When some women declared their intention to participate once Nov. 1 rolled around, backlash from men and other women was fierce.

Yesterday, popular Twitter parody account @FillWerrell tweeted, “Girls who participate in No Shave November will also participate in No D December.” The tweet has been reblogged nearly 17,000 times since yesterday and prompted a flurry of Twitter mockery. This post by Tumblr user timeturner, which collected some typical Twitter reactions to the idea of women not shaving for a full month, racked up over 20,000 notes yesterday before the user wiped the Tumblr account.

To make things even more, err, hairy, many participants in the online debate are mixing up No Shave November with Movember. Movember is a month-long mustache-growing contest that raises money for prostate cancer research. No Shave November is more of a college tradition. It’s not a charity campaign and is purely about being lazy and letting your razors lie dormant for the month. But though the official rules of “Noshember,” one iteration of the challenge, includes girls in the challenge, another version, No Shave Nov, confines the challenge to the “manliest beard.”

But the confusion has led some men to feel as though women are encroaching on a distinctly masculine endeavor.

“Feminism can’t have this one, not everything is about people with vaginas!” wrote chunkymonkeyandme on Tumblr. “[D]o not take this prostate cancer awareness month away from men and make it about feminism and your rights not to shave!”

The Movember contest does allow for “Mo Sisters” to participate, however. They’re encouraged to do this primarily by supporting their mustache-growing male friends, but there’s also a growing trend of women wearing fake mustaches for the month.

Yet the reaction from around the Internet to the thought of women with actual hair, facial or body, seems to be a range of disgust and indignation. The reaction has prompted some women to participate purely out of spite: “I wasn’t going to participate in no shave november,” wrote superherohunter on Tumblr, “but this morning my principal goes ‘oh and ladies we don’t encourage you to do this, just the guys.’ it’s stuff like this man :/”

Perhaps we might want to change the name of this challenge to No Shame November.

Photo via paulamunro1/Instagram