NaNoWriMo sounds like an odd foreign language which shouldn't be trusted. It looks like someone failed hardcore at an acronym...and that notion isn't too far-fetched. If you have friends who are writers, or friends who write with a dedication will either shudder in fear or be taken over by a mad streak and begin to mutter incoherently, potentially growing dark bags under their eyes during the course of the question.
National November Writing Month is an event for anyone who has ever thought about writing a novel. It's an accountability website for any and all writers who want to advance their product game, ideally to push a participant into completing a novel. All you need to do is create an account, create a small bio about your novel, and on November 1 start a new Microsoft Word document and get typing!
But, dear friends, this isn't only a shameless plug for a great event I've participated in (my sophomore year I made it to 48,000 words...so close! Curse you Oklahoma!), this is also a small guide on how to support your friends. Keep in mind these poor souls have basically signed their own death certificate, agreeing to crank out the equivalent of a novel among the hustle and bustle of their daily lives. To keep themselves at max sanity, the writer needs to produce about 1,666.67 words per day. They also must navigate writer's block, sporadic life events grasping after concentration and either enough pre-writing to keep their plot alive, or, if you're like myself, enough plot improvisation skills to keep a story alive.
Your friend who has decided to sign away their free time for the next solid month may start out peppy, hopeful even, as they grow excited over the birth of their creation. They may feel a completely appropriate high at seeing their words actually coming from their brains and flowing onto paper, becoming concrete and tangible. Celebrate them, give them extra smiles and hugs (if they want them) and compliments.
About halfway through week two they may hit their first plot hole, writer's block, or simply start thinking too hard about all of the grammatical and over-explaining rife throughout their story. Encourage them to jump right over that plot hole, get a different perspective to conquer the block, and don't forget to help them tie up the editor and throw them back in the closet for the next two and a half weeks. Finally, when they drag into the last week, maybe nowhere near their word count, most likely almost there, and if you have a special unicorn who only eats unblemished neon Trix and never smells weird, they might be done already. Buy them coffee, write them nice letters, and offer them a night out once it's December. They probably haven't gone outside anywhere for a long time.
To the friends of dedicated and potentially unstable writers, November is coming.
To the writers, I lift my glass to join you on this journey, and may the words flow freely, distractions be silent and your muse be merciful!