A celebration of manliness and our natural state in which for the entire month of november, men will grow their beards regardless of age or ability to grow a full beard. Women can participate by not shaving their legs, but this is not required of them.
Guy#1: Hey man, what's up with the beard?
Guy#2: It's neanderthal november, you're not allowed to shave until December 1st or later.
Guy#2: I can't participate, my beard grows really patchy.
Guy#1: No worries, Neanderthal November isn't about beards, it's about being as manly as you can be.
Guy#2: *Throws razor in the garbage*
Guy#1: Now you're getting it. Now let's go pillage a weaker tribe