When you see a room full of only men, figure out the odds of that happening at random.
A room with 1 person, it's 1:2 chance of all men. With 2 people, 1:4 chance. 3 people, 1:8 chance, etc. 2 to the power of X.
It's literally a 1 in a 1,000,000 chance that a room with 20 guys and no other genders would happen at random.
Or a 99.9999% chance there's something keeping other folks out.