I'm old school. It should have a purpose and it should not be done in a way where it could really injure a child. A period of physical discomfort should suffice. Then tell the child why the whoopin was administered. If you fail to discipline physically what is to stop the child from getting out of line. Nothing wrong with a smack in the mouf for an uruly kid cursing their mother. It teaches humility in a cruel world. The parents teach that the pain in the real world > a whooping. The world outside of your family don't give a fuck about you. These kids are disrespectful to grown ups because they have no fear of being handled.