What is the worst thing a parent can do to their child ? Why?

The worst thing a parent could do is whip there child in school. The child would be so embrassed . The child wouldn't want to show their face again. Kids would tease them. They would get into fights. I think the parent should just wait to they get home to disipline their child. The child might be quite for the rest of there life. That could mess them up for a good oppurinty.