My childhood best friend, his mom was a hard ass. She beat him up twice that I recall (and was aware of).
Once we were 12 or 13, and we hung a string across the street, with a small tree branch dangling down from the middle of it. So a car would not be able to pass without hitting the stick. A car came, stopped, and started honking the horn. Of course we had run away at this point.
The next morning, his mom drove both of us to school. (She took turns with my mom driving us to school). My friend had a nice black eye, and I could see smoke coming out of his mom's head during the drive. I didn't say a word.
The second time, my friend was about 20. He had started going to the casinos and off track betting. He won something like 11k. He made the mistake of telling his mom. She beat the shit out of him again, angry at him for gambling.