The common meaning of "sex" follows the principle of one-to-one correspondence. Even if it is precisely calculated to the number of entries and exits, there will be no situation where one side is more and the other side is less. This one-to-one relationship can basically confirm a fact, that is: an act of lewdness always corresponds to a man and a woman. However, the word "lewd" has become a derogatory term, only applicable to women. Women are very afraid of being labeled as "lewd". A woman once said to me: You must think I am lewd. I was very surprised.