I think it started as No Shave November for prostate cancer awareness, then somewhere along the way the internet started memeing No Nut November the same way Dicks out for Harambe became a meme and then now supposedly it's been co-opted by incels. No Shave November then changed to Movember, although they may be interchangeable. At least that's the timeline I recall it happening.

You probably never heard of it because it didn't happen. It was a joke on social media that snowballed, as memes tend to do.