Say hello to my lil' friend...

So, I'm walking down Mass. Ave today and I hear yelling. It's coming from a skin-headed man with loads of tattoos, standing with a woman and two small children. The man is screaming at a young girl, who looks to be about five, and grabbing at her arm. He says through gritted teeth, "When we get home, I'm going to give you a SPANKING, ok?" The girl and boy, who is about three, are both weeping softly and looking terrified. As I walk past them, the two adults are too involved to notice that I am watching. About 20 yards away, I turn around to see what is happening. I watch the man scream, "Do you see what the sign says? DO YOU SEE WHAT THE SIGN SAYS?" Then he hits the little girl in the face. At this point, the woman looks up and sees me watching. The man looks at the woman and then at me. For a moment, our eyes meet and my eyes narrow as I give him a quizzical look, as if to say, "Do you realize what you're doing?" I turn on my heel, and casually walk away as he screams unintelligible curse words at me.
Have you ever wished for a police badge and a gun? I sure have. This would have been the perfect situation for it. I would have walked confidently up to the couple, put the badge up with my left hand, grasped my gun in the holster and said, "Elbow... Boston P.D. Did I just witness you STRIKE that little girl in the FACE?" Man, it would have been sweet to have the authority to get up in his face and make him feel one IOTA of the fear that the little girl was feeling. It really boils my blood to see adults treat young children like that. I've been working with five-year-olds for almost 20 years and no child has EVER done something that would make me that mad. People like that need a good dose of fear and authority staring down on them. What I wouldn't give to scare him just enough for him to pee in his pants just a little...