This is an event to raise awareness, usually for prostate cancer, but for men's health in general. The month of November has been dubbed Movember, and participants are dubbed either Mo Bros or Mo Sistas; Mo being short for Moustache.
To participate, you start off with a clean shave on October 31st, and do not shave your moustache for the entire month of November, and then resume your regularly scheduled shaves on December 1st. While this is generally a men's event, women are welcome to show support as well, via other means.
No Shave November