Dad was an Airborne Ranger. Little dude, 5-10, 165. I'm quite a bit bigger than he was.
I was 14 and we were sitting at a stoplight and the car next to us had the typical group of college guys mouthing the car in front of them. My dad looks over at them as most anyone would when people are yelling obscenities around their kid. The guy in the back of the car gets out of the car and walks around to my dad's front door and opens it up and tries to punch him.
My dad blocked his punch, hit him in the throat so he fell down. He stepped out and in one motion flipped his leg up on the floorboard of the car and then stomped his knee. The dude was screaming as he laid there. Dad got back in, shut the door, waited for the light to turn green and drove off. Never said a word.
My point is you'd never have guessed he was the way he could be and I learned that day that despite my teenage bravado, I could, in fact, NOT take my dad.