Yes, I have.

My parents had a habbit of beating me and my sister with an extension cord. It was seen as an acceptable discipline method. They were otherwise very caring, but almost any misbehavior lead to the extension cord punishment.

Several years in I became almost numb to that physical pain, but the marks on the body were humiliating. A couple more years later, when I was about 13, when my mother took a swing at me once again, I guarded myself with my forearm, and tore the cord out of her hands. At that point I couldn't contain myself. I lashed out at her, started beating her up with that cord with all the strength I had. She started crying, screaming that it's not how a man should treat his mother, and so on. My rage had passed, so I just threw the cord at her and went to my room. That is when the beatings finally stopped.

My dad beat me much less often, but when he did he was a lot more violent than my mom. At one point he beat me up with the very same extension cord until I was on my knees, then he beat me up more because "don't you ever dare kneel in front of anyone", then he made me call myself a piece of shit and beat me up some more because "my son is not a piece of shit". He seemed to cool off after that, but when I got up he started choking me with the same damned cord. When I was about to pass out, he let go, told me he loved me and left the room.

Next time he got mad with me I landed the first punch. Managed to put him on the ground and armlock him. Broke his finger in the process. While he was on the ground he screamed that I only put him down because he let me. Nevertheless, ever since then he backs off when he sees that I'm about to lose it.

The funny thing is they still don't think they did anything wrong. They say that it was me who was a troubled teenager. My father says I'm insane for remembering the beatup he gave me, since "family is about good things".

Now, I'm not proud at all of fighting with them. But it turned out to be the only way to stop physical punishments, which were sometimes getting out of hand, so I am not ashamed of that either.

P.S. Damn, that's a wall of text! Guess I needed to vent. Hope you don't mind, OP.