International Men's Day was November 19. You missed it, probably because companies don't see pandering to men as nearly as profitable as pandering to women. International Women's Day is for brands. They celebrate it with pink beer, feminised logos, and lip service to equality.
If you're a dude and you'd like to celebrate your own day, do not spend today asking women when your day is. Use this time — you have almost a year — to plan your International Men's Day party.
Will you have beer but put blue labels on it? Will you make a video about how you value the male employees at your company, like theoretically, but not enough to protect them from harassment? Will you petition McDonald's to turn their logo right-side-up so it starts with the same letter as the word "men," because that makes you feel really empowered?
Anyhow, have fun with that. Your party budget is bigger than ours anyway.