The idea that men are not supposed to hit women is based on the belief that men are strong and women are weak and unable to hurt a man. This is sexist as hell, and flat out untrue. Woman can be strong, and violent. The idea that men are just supposed to take it is based on outdated beliefs about sex roles. Don't hit anybody. If someone hits you, you don't have to allow that and may defend yourself. It doesn't give you permission to beat them down.