Here's how it works:
...If you're a woman, you subtract one.
...If you're a man, you add one.
So if the number is 62, and you're a man, you would add one to make 63.
If the number is 62 and you're a woman, you would subtract one, to make 61.
The only rule is that you can only post once per turn--i.e., you would have to wait for at least one other person to post before posting again.
I'm a woman, and 0 - 1 = -1.
So ~ the number is currently -1.