I am assuming this thread about belly punching is not serious and more about a fantasy. You would probably be in jail about 20 minutes after punching some strange woman in the stomach IRL. I remember there was a guy in Nashville who would wear shoes with big wooden blocks attached and stomp women's feet. He got beat up numerous times and did several stretches in jail and mental hospitals. And I think he finally killed himself.
I know that's not the same thing but if you're actually contemplating punching someone you should probably rethink it.